Wordle.net is awesome! I typed a list of my favorite bands, played around with the fonts and colors, and got this!
(click to see a larger image)
To make a list of occurence-weighted artists off of iTunes you can follow these steps*
1) In iTunes, select View Options under the View menu.
2) Turn off everything but “Artist.”
3) Select all and copy.
4) Search and Replace the word “track” with nothing.
5) Paste the results into the Wordle.net Create page.
*From Scott Westerfeld's blog