N900 could be used as a car video recorder to have proof in case of trafic incidents (like proof you didn't run a red light etc). Also, the camera software needs to run in the background so other applications like Ovi maps can run in the foreground.
Requirements:
1. A car holder that does not obstruct the camera lens
2. The camera software needs an option to keep recording when not running in the foreground
3. The camera software needs options to be able to record in smaller resolutions. Or, easier to implement and preferable, a wrap-around feature: record 30 minutes (user configurable duration) in file1, then record the next 30 min in file2, then overwrite file1 with the next 30 min and so on. This way you would have a record of the last 30+ minutes at all times.