Digg-like function on objects

Hello all,

I've really begun to dig what I'm experiencing when I'm testing out Elgg with various mods and tweaks. But one thing haunts me, the one thing that will be the killer app on my planned site. The function where users can digg an object, which I as site admin later can use in order to present objects on the Dashboard according to how many diggs it has got.

I know my way around php and I have begun to glance a bit at the documentation of Elgg, but I'm not yet ready to dive head on and begin to code this function.

Anyone got any clues, hints or helping hands in order to get such a mod produced? I know that ArtFolio got a rating system included, which is one item to look into and then adapt.