Use the [cloud words="Awesome,Fabulous"] shortcode to create a cloud of words

word-cloud.php

<?php
/*
Plugin Name: S11 Word Cloud
Description: Use the [cloud words="Awesome,Fabulous"] shortcode to create a cloud of words
Version: 1.0
Author URI: http://strategy11.com
Author: Strategy11
*/

add_shortcode( 'cloud', 's11_word_cloud' );
function s11_word_cloud( $atts ) {
	$atts = shortcode_atts( array(
		'words' => 'Awesome, Fabulous',
		'colors' => '#21759b, #d54e21, #464646',
	), $atts );
	$colors = explode( ',', $atts['colors'] );
	$words = array_filter( explode( ',', $atts['words'] ) );
	$words = array_map( 'strtolower', array_map( 'trim', $words ) );
	$words = array_map( 'ucwords', $words );
	$word_counts = array_count_values( $words );
	$sorted = $word_counts;
	arsort( $sorted );
	$highest_count = reset( $sorted );

	$max_size = 75;
	$min_size = 10;
    $step = absint( ( $max_size - $min_size ) / $highest_count );

	$weighted = array();
	foreach( $word_counts as $word => $count ) {
		$weighted[ $word ] = $min_size + ( $step * $count );
	}

	$color_pointer = 0;

	$all_words = array();
	$cloud = '<ul class="s11cloud">';
	foreach ( $weighted as $word => $size ) {
		$all_words[] = '<li style="font-size:' . absint( $size ) .'px;color:' . esc_attr( $colors[ $color_pointer ] ) .'">' . trim( $word ) . '</li>';
		$color_pointer++;
		if ( ! isset( $colors[ $color_pointer ] ) ) {
			$color_pointer = 0;
		}
	}

	shuffle( $all_words );
	$cloud .= implode( ' ', $all_words );
	$cloud .= '</ul>';

	s11_add_cloud_style( $cloud );

	return $cloud;
}

function s11_add_cloud_style( &$cloud ) {
	$cloud .= '<style>ul.s11cloud {
    	max-width: 500px;
    	padding: 30px 10px;
    	text-align:center;
		margin:0 auto;
		line-height: 1;
	}
	.s11cloud li{
		display:inline-block;
		list-style:none;
		padding-right:3px;
	}
	</style>';
}