There are several Bluetooth profiles that are not officially supported in Maemo 5 (e.g. BT keyboards) but are however supported by the upstream BlueZ project or can be made to work with some simple hacks.

There is an initial wiki page documenting them: http://wiki.maemo.org/Fremantle_Unsu...tooth_profiles

Johan Hedberg, lead BT developer in Maemo Devicves and BlueZ maintainer, will have a session about this topic in the Maemo Summit. Marcel Holtmann and Luiz von Dentz, both BlueZ maintainers familiar with Maemo, are attending as well.