in any case, get debian on your device
it expands the application library and possibilties of using the n900.
also get:
psx4m-gui (pcsx-rearmed)
leafpad
qtmobilehotspot
syobon action
slysics
conky and it's layoutswitcher
opera mobile
faster app manager
mplyer
cutetube-qml

that is mostly everything i need everyday to get happy with my N900