I have made a couple of N900 applications over the past few weeks. They are both available from the maemo-extras repository. I thought you might like to hear about them.

rfk (robotfindskitten) is a port of Leonard Richardson's abstract game to Maemo.

Belltower is an application to find belltowers hung for change-ringing. It uses the data from Dove's Guide, which they say can be freely reused. The program lets you find the nearest belltowers using the GPS, and search by area and name. At present Dove's Guide is included in the archive, but I'm planning to make the program download it from the Dove site. There are some screenshots here. I'm not sure how many people will find this useful, but I think it shows off some of the device's capabilities quite nicely.