I suppose it depends on which "rank" we're talking about. One thing I'd like to explore is to find some way to equate the "rank" seen in the Fun Facts (and signature) with the standing you see in the "Top Collectors" list, such that if you are #1 in the Top Collectors list, then your rank is also #1. Right now there's a disconnect--you can be #1 in the top collectors, but have some totally different rank in the Fun Facts. The Top Collectors list shows a ratio, the number of items you own over the total number of items available in the category. Right now there is no finesse in determining if you "own" a toy or not--we simply give you full credit for owning the toy if you have used the "Add to my collection" link. In other words, a guy that owns a MISB g1 optimus prime would get the same credit as a guy that only has the left fist.
I think determining "ownage" credit might work along the lines Spaceharfang describes, such that you have to pass some threshold score, with figure parts having a heavier weight than accessories. Another thing I want to do is caution about giving too much importance purely to "figures". Not every toy actually includes a proper figure, yet you can be sure that the collectors that own them want credit for them. And shmax.com will eventually expand to other toylines (Star Wars, G.I. Joe), so any system we come up with should be versatile enough to handle those as well.