There is a threaded comment system to collect ideas over on the blog called the Idea Forum. Please put your ideas there.

Lets get a list started. If you have an idea, throw it in the list:

1. Zillow for commercial real estate. How handy would it be to have Zillow-like functionality for office leases etc. Zoom in to an area and see what people are paying i.e. some kind of Google Maps mashup. I'm just not sure where we get the data from.
2. Tools for a StartupWeekend. How about a bundled set of tools to roll out a StartupWeekend (or any other kind of intensely collaborative short project). The idea would be to combine multiple open source apps into an easy to install/setup bundle.
3. CraigsBuddysList. Shopping/comparison engine for used goods. Polls ebay and craigslist to find specific used items...