1. Staffan I. Lindberg's Elections and Democracy in Africa 1989-2003 dataset: Its codebook and the SPSS data file are downloadable from his website.
2. http://africanelections.tripod.com: Probably the best source for election results in Africa. But this database relies only on websites as its information sources, perhaps due to copyright concerns.
3. Dieter Nohlen, Bernard Thibaut, and Michael Krennerich eds. Elections in Africa: A Data Handbook (Oxford University Press, 1999) http://dx.doi.org/10.1093/0198296452.001.0001: This book covers even pre-independence election results.