I hope everyone in this thread is aware of "volumecontroldaemon".

It boosts the N900 volume by 12% in all cases: calls, music and speakers. It does this by removing the 12% volume nerf by Nokia.

You need to have extras-devel enabled to find it and install. I've had it a couple of months now (with and without CSSU) and it works fine. Gives that extra boost we've been waiting for.