Well, after my last idea went down horribly, I thought I'd raise another on the forum.
How about pictures in Skritter for definitions?
Boo-ya, boo-ya!
...Well in fact, if you're testing the custom definitions (or are they site wide yet?) you can already have them. Just add html to the definition field. I suggest searching google images with "icons" selected on the left to get the right size. Then maybe upload someplace else for safe keeping.
Cheers Nick, this is very cool, and will certainly help retention.
http://tiny.cc/cqf5b