Here are some of the more useful BGC links. Almost every aspect of BGC is going to be covered in at least one of these in better detail than I have used.

The Bubblegum Crash! Website
Bubblegum Crisis
BGC/AD. Police Synopses
Mega Tokyo 2033 Bubblegum Crisis
BGC: Dawn of the Knight Sabers
A Fool's Guide to Bubblegum Crisis
TokyoNet
The Beginner's Guide to the Knight Sabers
The Shrine to Sylia Stingray and Largo
Bubblegum Crisis Info and Review
Sylia Stingray's Page of Bubblegum Stuff
Raven's Garage--The Technology of Bubblegum Crisis
BGC Links of Links