O/T:Engine Management

I have to do a paper for school on aftermarket engine management. It needs to explain what it is, what it does, and so on. Do any of you guys know any good sites where I can find some information? Does anyone have any ideas for my paper?

Thanks.

Go to google and search for info on the:
Greddy E Manage
AEM Programable Engine Management System
Apexi VAFC

Just to name a few.