If you had forgotten all about Slamball it's not just you. Totally forgot about it until I came across this video by Mike Korzemba on YouTube. If you've never heard of it and I likely won't do it justice with this description, but it was sort of like basketball with football elements... and oh yeah trampolines. It hit the scene in 2002 and I believe Spike TV was the main channel that broadcast it.
Anyway you'll likely get all the info you need from the abive video, though it concentrates more on the demise of the sport.