Minitwitter in full javascript both client/server side with mongodb and nodeJS -- full app available on https://github.com/sgodbillon/minitwitter

mongo.js

// Full source code available on https://github.com/sgodbillon/minitwitter

var nmnLocation = '/path/to/node-mongodb-native'

var	Db = require(nmnLocation).Db,
 	Server = require(nmnLocation).Server;

var host = 'localhost';
var port = 27017;

var getTweetsCollection = function(callback) {
	var db = new Db('minitwitter', new Server(host, port))
	db.open(function() {
		db.createCollection('tweets', function() {
			db.collection('tweets', function(error, collection) {
				console.log(error)
				callback(collection)
				db.close()	
			})	
		})	
	})
}

this.createTweet = function(tweet, callback) {
	getTweetsCollection(function(collection) {
		collection.insert(tweet)	
	})
}

this.listTweets = function(search, callback) {
	var filter = {}
	if(search.message) {
		filter.message = search.message.replace(/[^\w\s]/g, '')
		filter.message = new RegExp('.*' + filter.message + '.*')
	}
	getTweetsCollection(function(collection) {
		collection.find(filter, {sort: [['date', 'descending']]}, function(error, docs) {
			var result = []
			docs.each(function(i, doc) {
				if(doc == null)
					callback(result)
				else result.push(doc)
			})
		})	
	})	
} 

nodeJS-mongo.js

/***** HTTP layer *****/

var SYS = require('sys');
var HTTP = require('http');
var URL = require('url');
var FS = require('fs');
var PATH = require('path');

HTTP.createServer(function (request, response) {
	var parsedURL = URL.parse(request.url, true)
	console.log('->', parsedURL.pathname)	
	
	// list tweets
	if(parsedURL.pathname == '/tweets' && request.method == 'GET') {
		var search = {}
		if(parsedURL.query && parsedURL.query.search)
			search.message = parsedURL.query.search
		require('./mongo').listTweets(search, function(tweets) {
			var result = JSON.stringify(tweets)
			response.writeHead(200, {
				'Content-Length': result.length,
				'Content-Type': 'text/json'
			})
			response.end(result)
		})
	// create a tweet
	} else if(parsedURL.pathname == '/tweets' && request.method == 'POST') {
		var obj = undefined
		request.on('data', function(data) {
			try {
				data = data.toString().replace(/\n/g, '\\n')
				obj = JSON.parse(data)
				obj.date = new Date().getTime()
				require('./mongo').createTweet(obj, function() {
					response.writeHead(201)
					response.end()
				})
			} catch(e) {
				console.log('data were', typeof data, data, 'e=',e)
				response.writeHead(500, 'Wrong data: not JSON?')
				response.end()
			}
		})
		request.on('end', function() {
			if(!obj) {
				response.writeHead(500, 'No data?')
				response.end();	
			}
		})
	// index
	} else if(parsedURL.pathname == '/' && request.method == 'GET') {
		var view = FS.readFileSync(__dirname + '/index.html')
		response.writeHead(200, {
			'Content-Type': 'text/html'
		})
		response.write(view)
		response.end()
	// static files
	} else if(parsedURL.pathname.indexOf('/public/') == 0 && request.method == 'GET') { 
		var path = __dirname + parsedURL.pathname
		path = PATH.normalize(path)
		if(path.indexOf(__dirname) != 0) {
			response.writeHead(403, 'Forbidden')
			response.end()
		} else {
			PATH.exists(path, function(exists) {
				if(exists) {
					var head = {}
					if(/css$/.test(path)) {
						head['Content-Type'] = 'text/css'
					}
					if(/js$/.test(path)) {
						head['Content-Type'] = 'text/javascript'
					}
					if(/png$/.test(path)) {
						head['Content-Type'] = 'image/png'
					}
					if(/(jpg|jpeg)$/.test(path)) {
						head['Content-Type'] = 'image/jpeg'
					}
					console.log('served static file', path, 'with head', SYS.inspect(head))
					response.writeHead(200, head)
					response.write(FS.readFileSync(path))
					response.end()
				} else {
					response.writeHead(404)
					response.end()
				}
			})
		}
	// not found.
	} else {
		response.writeHead(404, 'Not Found!!')
		response.end()
	}
  
}).listen(8124);

console.log('Server running at http://127.0.0.1:8124/');

zentweet-client.js

$(function() {
	var makeTagLinks = function(str) {
		return str.replace(/(#\w+)/g, '<a class="tag" href="#">$1</a>')
	}
	
	var createTweet = function(tweet, callback) {
		$.post('/tweets',tweet, function() {
			console.log('created tweet', tweet)
			if(callback) callback()
		})
	}
	
	var listTweets = function(params, callback) {
		$.get('/tweets', params || {}, function(data) {
			console.log('list tweets', data)
			if(callback) callback(data)
		})
	}
	
	var updateTweetList = function(params) {
		listTweets(params, function(data) {
			var $ul = $('#tweets ul')
			$ul.children().remove()
			$.each(data, function(i, tweet) {
				$ul.append('<li><img src="/public/images/zengularity-logo-without-name.png" class="picture"/><a href="#" class="user">SGO</a>' + makeTagLinks(tweet.message) + '</div></li>')
			})
		})
	}
	
	$('#new-tweet form').submit(function() {
		createTweet(JSON.stringify({"message": $('#message').val()}), function() {
			updateTweetList()
		})
		return false
	})
	
	$('#search').submit(function() {
		updateTweetList({search: $('#search input').val()})
		return false
	})
	
	$('.tag').live('click', function() {
		$('#search input').val($(this).text())
		$('#search').submit()
		return false
	})
	
	updateTweetList()
})

zindex.html

<html>
	<head>
	<title>Home</title>
		<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
		<link rel="stylesheet" type="text/css" media="screen" href="/public/stylesheets/main.css">
		<link rel="shortcut icon" type="image/png" href="/public/images/favicon.png">
		<script src="/public/javascripts/jquery-1.4.2.min.js" type="text/javascript" charset="utf-8"></script>
		<script src="/public/javascripts/zentweet-client.js" type="text/javascript" charset="utf-8"></script>
	</head> 
	<body>
		<header>
			<a href="/">Zentweet</a>
			<form id="search" action="#" method="post">
				<input type="text" placeholder="search" name="search" />
			</form>
		</header>
		<article id="new-tweet">
			<form action="#" method="post">
				<div>
					<label>What's happening ?</label>
					<textarea type="text" name="message" id="message"></textarea>
				</div>
				<div>
					<input type="submit" />
				</div>
			</form>
		</article>
		<article id="tweets">
			<ul>
			</ul>
		</article>
	</body>
</html>