First, I would like to qualify this comment by saying that I really enjoy what Zam has provided to the Rift community. The soul builder, quest database, and other facets of the site are very well done and I use this site almost exclusively as it relates to my Rift needs.
That said, the one (simple) thing that I think would really bring a lot of usability and functionality to this site is to be able to add weights to stats on items that you're filtering for. The best example that I've seen of this would be at Magelo. Here is a sample link to a search for Planar Essences that have the desired weights I'm looking for.
To be able to sort and filter essences (or any other item for that matter) based on a variety of calculated stats is not very easy the way that Zam's filtering is currently set up.
Anyway, this is something that is very simple, in concept at least, and would help your users get even more benefit from your site.