6 buttons + dpad at a minium should be fine as start + select can be keys on the N900 as you do not have to use them often.

Most games dont even make use of all 6 of the main buttons so just depends on the game.

Anyways, there maybe hope in this product I mentioned it once before but I think that post/thread fell into the abyss:

http://go.notebookreview.com/?id=525...23ht_917wt_728

Its a direct connection via usb for 2 wii classic controllers it works on almost all PC platforms, but no drivers for linux. Since the N900 has a usb port, with an adapter and a good devolper chances are this product will work.

I just ordered one but I have no clue how to program it to work on the N900 and I highly doubt it will be plug & play (though it may show up has a HID device...)

Unfortunately the N900 has no Host Mode USB Port. (USB On-The-Go / USB OTG)

You must create your own Bluetooth adapter first. I suggest disassembly a Bluetooth keyboard and connect the Buttons from your new controller to the buttons you want to use. But this hack wouldn't work with analog components. (sticks etc.)

But is this worth the work?

No.

Some has the PS3 Sixaxis working. That's the way forward.

Mmmh... Okay... I'm old and forgetful. But I'm very sure. The PS3 Sixaxis is a Bluetooth Controller. Am I wrong?

You can connect it to USB. But only to charge the battery.

yes, its a bluetooth controller.