Hi there, i've just completed a fix for a N900 that had its USB port ripped out with the cable and this fix may be of interest to some. Basically the pads and the connectors all got damaged meaning that the USB socket was unusable and an alternative was needed that didn't require shopping.
For this I decided to see if I could get a small charger port into the phone and the smallest available was from an old busted Nokia 6280, the port is really tiny.
I found an area that was free for this after some Dremel use, just near one of the speakers.


The socket then got glued to the main board in this location below -



Resulting in a little charger socket that was visible via a hole drilled into the outer case -



The charger is the original 5v, 850mA one that came with the 6280, its using the USB circuit but thats rated for the N900 charger of 1200mA so it shouldn't be a problem. The data+ and data- pins were soldered together without a resistor bridging them.

This might not be the most elegant solution but given the restraints of not having much equipment, minimal soldering experience and an iron that was too large for the tiny tiny SMB type stuff.

I hope this may help some and I only offer this as it was the great info and posts available here that made my fix possible, so thanks!