Some people may consider ikiwiki's default look to be a bit plain. Someone on slashdot even suggested perhaps it uses html 1.0. (Yes, an ikiwiki site has survived its first slashdotting. With static html, that's not very hard..) While the default style is indeed plain, there's more fine-tuning going on than you might think, and it's actually all done with xhtml and style sheets.
Stefano Zacchiroli came up with the idea of adding a css market page where IkiWikiUsers can share style sheets that you've come up with for ikiwiki. This is a great idea and I encourage those of you who have customised stylesheets to post them.
I'm also always looking for minimalistic yet refined additions to the default style sheet, and always appreciate suggestions for it.