Controlling a Arduino using Twitter. You will need to download the Twitter4J library on http://twitter4j.org then import all the .jar files in the processing IDE.

JosKartEngine.pde

//This code has to be opened in the Processing IDE, put it in the same folder as the JosKartTwitter.pde
//We are gonnna use the Twitter4J library.
import twitter4j.FilterQuery;
import twitter4j.StallWarning;
import twitter4j.Status;
import twitter4j.Twitter;
import twitter4j.TwitterFactory;
import twitter4j.TwitterStream;
import twitter4j.conf.ConfigurationBuilder;
import twitter4j.StatusDeletionNotice;
import twitter4j.StatusListener;
import twitter4j.TwitterStreamFactory;

public class JosKartEngine {
    Twitter twitter;
    TwitterFactory twitterFactory;
    TwitterStream twitterStream;
    String[] directions = {"MOVEFORWARD", "MOVELEFT", "MOVERIGHT", "REVERSE"};
    String direction = " ";
    double distance = 0;
    double calculatedDistance;
    int secondsPerCM = 1507;
    
    public void initConfig() {
        ConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
        configurationBuilder.setDebugEnabled(true)
                .setOAuthConsumerKey(" ") //you will need to use your own Twitter Dev credentials.
                .setOAuthConsumerSecret(" ")
                .setOAuthAccessToken(" ")
                .setOAuthAccessTokenSecret(" ");
        twitterStream = new TwitterStreamFactory(configurationBuilder.build()).getInstance();
        println("CONFIGS ARE DONE");
    }

    //get a number from the tweet
    public String getDistanceFrom (String theTweet) 
    {
        if(theTweet == null || theTweet.isEmpty()) {return "0";}
        
        StringBuilder stringBuilder = new StringBuilder();
        boolean foundDistance = false;
        for(char c : theTweet.toCharArray()){
            if(Character.isDigit(c)){
                stringBuilder.append(c);
                foundDistance = true;                    
            } else if (foundDistance) {break;}
        }

        return stringBuilder.toString();
    }
    
    public void stopMovementAfter(int actualDistance)
    {
      delay(actualDistance);
      serial.write(stopMoving());  
      println("Distance covered...skirr");//I shouldn't have this here
    }

    public void listenOnTweets()
    {
       StatusListener statusListener = new StatusListener(){
       
           @Override
           public void onException(Exception ex) {
               System.out.println("ERRRORR: " + ex);
           }
       
           @Override
           public void onTrackLimitationNotice(int numberOfLimitedStatuses) {
                System.out.println("LIMIT: " + numberOfLimitedStatuses);
           }
                  
           @Override
           public void onStatus(Status status) {
                String theStatus = status.getText().toUpperCase();         
                //the distance
                try { distance = Integer.parseInt(getDistanceFrom(theStatus)); 
                } catch (NumberFormatException ex) { 
                  System.out.println("OOPSS...numbers game: " + ex);                  
                }
                // the most magic happens on line 84 and 85
                calculatedDistance = (distance/28.571) * 1000; //28.. is the estimated speed of the motors on full throttle 
                Integer timeLapse = Integer.valueOf((int) Math.round(calculatedDistance));//T = D/V * 1000 seconds
                
                System.out.println("\n\n-------------NEW TWEET-----------------");
                System.out.println("\nTWEET: " + status.getText() + " BY: " + status.getUser().getScreenName());     
                if (theStatus.contains(directions[0]))
                    {                     
                        println("\n\n--------Extracted Data-----------");
                        println("Direction: " + directions[0] + "\nDistance: " + distance + "\nTravel Time: " + timeLapse + " milliseconds");
                        serial.write(moveForward());
                        stopMovementAfter(timeLapse);
                    } else if(theStatus.contains(directions[1]))
                    {                       
                        println("Direction: " + directions[0] + "\nDistance: " + distance + "\nTravel Time: " + timeLapse + " milliseconds");
                        serial.write(moveLeft());
                        stopMovementAfter(timeLapse);
                    } else if(theStatus.contains(directions[2]))
                    {                        
                        println("Direction: " + directions[0] + "\nDistance: " + distance + "\nTravel Time: " + timeLapse + " milliseconds");
                        serial.write(moveRight());
                        stopMovementAfter(timeLapse);
                    } else if(theStatus.contains(directions[3]))
                    {                       
                        println("Direction: " + directions[0] + "\nDistance: " + distance + "\nTravel Time: " + timeLapse + " milliseconds");
                        serial.write(moveBackward());
                        stopMovementAfter(timeLapse);
                    } else {
                        System.out.println("CAN'T READ DIRECTION & Distance (maybe)");
                    }
                    System.out.println("\n-------------END TWEET-----------------");    
           }
       
           @Override
           public void onStallWarning(StallWarning warning) {
            System.out.println("STALLING: " + warning);   
           }
       
           @Override
           public void onScrubGeo(long userId, long upToStatusId) {
            System.out.println("USER: " + userId + " : " + upToStatusId);   
           }
       
           @Override
           public void onDeletionNotice(StatusDeletionNotice statusDeletionNotice) {
            System.out.println("DELETING STATUS: " + statusDeletionNotice); 
           }
       };

       
       //the magic is here..a bit of it
       FilterQuery filterQuery = new FilterQuery();
       String keyWord = "#redbullbasement"; //you can use any keyword of choice.
       filterQuery.track(keyWord);
       twitterStream.addListener(statusListener);
       twitterStream.filter(filterQuery);

    }
}

JosKartTwitter.pde

//This code has to be opened in the Processing IDE, put it in the same folder as the JosKartEngine.pde
import processing.serial.*;

Serial serial;
JosKartEngine josKartEngine = new JosKartEngine();

void setup()
{
  josKartEngine.initConfig(); //start the engine
  size(400, 200); 
  serial = new Serial(this, "COM14", 9600);
  josKartEngine.listenOnTweets(); // I dont think this will work...lol
}

void draw()
{
  
  background(0);
  //textAlign(CENTER);
  //drawType(width * 0.5);
}

int moveForward() { return 1; }
int moveBackward() { return 2; }
int moveLeft() { return 3; }
int moveRight() { return 4; }
int stopMoving() {return 0;}

void drawType(float x) {
  line(x, 0, x, 65);
  line(x, 220, x, (height * 0.5));
  fill(255);
  text(directionText, x, 95);
}

JosTweet.ino

//This code has to be uploaded to the Arduino
const int motorAForward = 11;
const int motorABackward = 10;
//motor B stuff
const int motorBForward = 9;
const int motorBBackward = 8;

int directionData;
void setup() {
  // put your setup code here, to run once:
  pinMode(motorAForward, OUTPUT); //set pin to output
  pinMode(motorBForward, OUTPUT); //set pin to output
  pinMode(motorABackward, OUTPUT);
  pinMode(motorBBackward, OUTPUT);  
  Serial.begin(9600);
}

void loop() {
 if(Serial.available() > 0) 
 {
  directionData = Serial.read(); 
  //move forward
  if(directionData == 1)
  {
    moveForward();  
  } 
  //movebackward
  if(directionData == 2) {
    moveBackward();  
  } 
  //move left
  if(directionData == 3) {
    moveForwardLeft();
  }
  //move right
  if(directionData == 4) {
    moveForwardRight();
  }
  if(directionData == 0){
    dontMove(); //this should work
  }
 }
  
}

void moveForward()
{
  analogWrite(motorAForward, 255);
  analogWrite(motorBForward, 255);
}

void moveBackward()
{
  analogWrite(motorABackward, 255);
  analogWrite(motorBBackward, 255);
}

void moveForwardLeft()
{
  analogWrite(motorAForward, 0);
  analogWrite(motorBForward, 255);
}

void moveForwardRight()
{
  analogWrite(motorAForward, 255);
  analogWrite(motorBForward, 0);
}
void dontMove()
{
  analogWrite(motorAForward, 0);
  analogWrite(motorBForward, 0);
  analogWrite(motorABackward, 0);
  analogWrite(motorBBackward, 0);
}