Most of these worked on my 6230 back in the day. (The ones about detecting radar and setting off shop alarms and such are bogus though, clearly.)

As was stated above, most of these were for Symbian devices where the primary interface was the dialer and/or a primitive menu system. As the interface evolves I'm sure most of them will vanish. I'm actually quite surprised anything beyond *#06# works, since I doubt there was much/any cross over code from S40/S60 into Maemo. (If there were, more phone-based codes & SDDS would have worked from the get go.)

The main reason for having *#06# work is it's usually the first thing a Nokia rep will ask for. With the IMEI code they can find the model/build and pick the right index card to start trouble shooting with.