Have you used Wordle to create word clouds from text? It is a lovely tool which allows you to tweak your clouds with different fonts, layouts, and colour schemes. Tom Barrett shares 52 (and counting) interesting ways to use Wordle in the following presentation.
Just be aware that unfortunately you can come across inappropriate content uploaded to the Wordle Gallery.
ABCYA.com has a number of activities on the site including a word cloud generator for children. It has simple functions to help manipulate your clouds, save them as jpegs and there is no option to upload to a gallery.
Or, if you prefer clouds in different shapes then try tagxedo