Jonathan Feinberg has made a cool application: Wordle. You give it a corpus of text, and it creates a word cloud with size based on frequency. Here are the titles of all my blog posts over the years:
Wordle automatically nestles all the words together, and when you create one, you can set parameters like font and layout algorithm. Very cool.
The thing that surprised me about my title cloud is that it looks like a tag cloud, but these are actually words pulled from the titles, not the names of tags. Maybe all that manual tagging isn't worth it after all?