I totally agree with some kind of stats on sales.
Maybe a total number of sales for each category over a month or quarterly period. Taking it even further would be a break down of how many different products were sold in that category, of course without disclosing which products they were. I often want to create new products for the Renderosity market but it takes a lot of time and effort to create and test these things and I can't afford to just guess what will be useful. I really feel that information of this type would be beneficial to all the merchants here. The wishing well is nice but often only caters to a few people. That doesn't justify creating a product.

Just my thoughts.