“You also hereby grant each user of the WikiMapia a non-exclusive license to access your User Submissions through the Service, and to use, reproduce, distribute, prepare derivative works of, display and perform such User Submissions as permitted through the functionality of Wikimapia and under these Terms of Service.”
However, items F., G., and I. only talk about non-commercial use.
Wikimapia is essentially derived from Google aerial imagery, so steer clear. Furthermore the license terms stipulate non-commercial use.
Sorry to go a bit purist on you but the best source of all is actually getting out there on the streets with your GPS unit - and I say that as one who has done significant amounts of armchair mapping but only where appropriate. It really is best to go out mapping on the ground for street names, points of interests and so on.