This is a great site, which I use a lot. Unfortunately I often have to go back to Google when looking for more advanced search options. Here are my suggestions.

1. By far, the most important option missing: sometimes, I want to search for an application witch has several words in it's description. E.g. "xls" and "pdf" (but not all "pdf" and all "xls").

2. I like open-source, but will settle for freeware. I should be able to search for everything free.

3. Some problems don't work in XP, 7, Vista, etc... There should be an option to select O.S..

Keep up the good work!

(EDIT)
4. Another interesting information to offer would be last version date (instead of number...)