Raw PHP for Wordpress / Songkick integration. Further work is needed on making this into a more robust function using Wordpress' current features.

wordpress_songkick.php

<?php 
  // Artist is custom field key for post
	$key_songkick = "Artist";
	// Check post to see if Artist custom field exists
	if ( get_post_meta($post->ID, $key_songkick, true) ) : 
		
		// Need to search by Artist name since we don't know ID, need ID to get the artist calendar.
		// Using urlencode since we can't send a space to the Songkick JSON request
		$Artist = urlencode(get_post_meta($post->ID, $key_songkick, true));
		// Use your API key here
		$jsonurl = "http://api.songkick.com/api/3.0/search/artists.json?query=$Artist&apikey=[YourSongKickAPIKey]";
		// PHP decoding JSON output
		$json = file_get_contents($jsonurl,0,null,null);
		$json_output = json_decode($json);
		
		// Setting variables for next query, mainly we needed the ID, but I'm using the URI and Artist name below in case we can't find any upcoming shows
		$URL = $json_output->resultsPage->results->artist[0]->uri;
		$ArtistID = $json_output->resultsPage->results->artist[0]->id;
		$Artist_Text = get_post_meta($post->ID, $key_songkick, true);
		
		// Using the ID we pulled from name search and decoding that JSON request
		$jsonurlCalendar = "http://api.songkick.com/api/3.0/artists/$ArtistID/calendar.json?apikey=[YourSongKickAPIKey]";
		$jsonCalendar = file_get_contents($jsonurlCalendar,0,null,null);
		$json_outputCalendar = json_decode($jsonCalendar);
		
		// if statement to make sure there are upcoming events
		if ($json_outputCalendar->resultsPage->totalEntries > 0):						
		
			// Building array from JSON request, this is to pull the first three items of course, but you can use dynamic array to make as many as you want.
			$ArtistCalendar = array (
				"EventName" => array (
					$json_outputCalendar->resultsPage->results->event[0]->displayName,
					$json_outputCalendar->resultsPage->results->event[1]->displayName,
					$json_outputCalendar->resultsPage->results->event[2]->displayName
				),
				"EventCity" => array (
					$json_outputCalendar->resultsPage->results->event[0]->location->city,
					$json_outputCalendar->resultsPage->results->event[1]->location->city,
					$json_outputCalendar->resultsPage->results->event[2]->location->city
				),
				"EventURL" => array (
					$json_outputCalendar->resultsPage->results->event[0]->uri,
					$json_outputCalendar->resultsPage->results->event[1]->uri,
					$json_outputCalendar->resultsPage->results->event[2]->uri
				)							
			);
		
			// Outputs full multidimensional array into site style
			foreach ($ArtistCalendar["EventName"] as $Key => $Name)
				{
				echo "<p><a href='{$ArtistCalendar["EventURL"][$Key]}' target='_blank'>$Name</a><br><span class='City'>{$ArtistCalendar["EventCity"][$Key]}</span></p>";
				}
		endif;
		
		// This will always display, but if there are no upcoming events, it will at least show this link so a user can follow a band on Songkick directly
		echo "<p>See upcoming shows for <a href='$URL' target='_blank'>$Artist_Text</a></p>";
		
	else:
		
		// If the Artist custom field was not set for the post
		echo "<p>Check out <a href='http://www.songkick.com/' target='_blank'>Songkick</a> to keep track of your favorite bands touring now.</p>";
		
	endif;							
 ?>