I'll be participating in the Wikithon next Wednesday at Socialtext's new office. My goal is to help people add identicon support to their wikis. If you are interested, join me at the Wikithon. Heck, even if it's not wiki-related, come on down and let's talk about your identicon application. Personally, I would like to see them in IMs and IRCs.
Adding identicon support to WikiCalc/SocialCalc will be interesting too since it is difficult to tell what each numbers in cells represent without looking at the column and row headers. One idea is to auto-assign each column and row labels then display them in cells on mouseover. So the number 512 is in Electricity column and January row, moving the mouse over the number would display identicon for Electricity and January.
I am working on another wiki-related idea which I might be able to show at Wikithon. All I can say for now is that it'll open up a whole new world for wiki users, not unlike the way WikiCalc does.