Many wikis out there use icons, or artworks, to wiki layout and/or presentation. For example (my apologies, only french links provided):

One good start would be to investigate what kind of icons we would like to have in our wiki:

Inspiration: see icons from wikimedia.

--jym

You've seen this, but others may not have: ikiwiki comes with some built-in icons we could be putting to better use. --schmonz