I have been using Tagxedo for the past few years as a sort of getting to know you tool. Students at the beginning of the year create a word cloud to introduce themselves to the class. This becomes handy in later units where students are studying text because they already have the ability to create the Word Clouds.
It has been a great interface, where you can get quite advanced. It has many templates and you can even upload any picture you want to create your Word Cloud. But I found another Word Cloud creator which runs a lot like Tagxedo but I feel has more features to allow you to customize it better. The website is called Tagul.
What I like the most is the ability to choose how big and what color individual words are. For example Milton in the above screen is size 42, and much bigger than the other words in the cloud. You must create an account in Tagul, but this is nice because then the program will let you save your projects for later use, this is a feature that Tagxedo does not have. The below graphic gives some benefits of creating Word Clouds in Tagul: