Had this chat, some weeks ago with a Nigerian developer in London. We would like to get people together who are interested in building/creating (things for Nigeria) not just small chops. I'm waiting for serious people to get back into London before organizing anything. I guess with my experience in running events, if you add food people will come, but we need serious people to come.
You should check out meetup and eventbrite, a fair bit of events are posted there. I may* be speaking at the LSE Africa Summit. So if you are around, say hi.