What is Ushahidi?

It's this thing that lets you report an incident using computers or mobile phones and then all incidents can be seen on a map.

Ushahidi may be useful this year in helping Nigerians monitor the general elections.
In the just completed Sudan voting, there was a phone number for the public to send text reports, and at SudanVoteMonitor you can see the map of voting disturbances.

If you're a software developer, learn more about ushahidi here.
If you just want to use Ushahidi, give Crowdmap a quick try