I love the Wordle site http://www.wordle.net/, but a 340 student (Thanks, Westley) shared the following site today which is even more useful and fun--http://www.tagxedo.com/. I can think of all kinds of applications for this-having students use country outlines and filling in with descriptors of the geography, culture, etc. or using heads of historical characters and again, using descriptors for those characters. When I was teaching in the pre-computer days, when the earth was cooling, I had historical head outlines that students would fill with images and phrases that described that person and this site reminded me of that!
I will say that I love typing in poems, historical documents, etc. to Wordle, then having students decide which poem or document the Wordle contains. It's a fun assessment to make sure they are familiar with specific vocabulary in those poems or documents.