Mongoose were bought out by Pacific Cycles (I think) and became really bad. However there were some good DH bikes in the late 90's and maybe 2000, like the NX DH and things like that. Now they are bringing out a bike called the balckdiamond which looks as though it could be a good bike. I also just bought a new bike, yesterday, which is a Mongoose DH. It however is not a normal Mongoose as there were only meant to be 2 ever made for Mongoose sponsored DHers in Australia, but they made 18 (or about that) for the Australian public.
If you want to see my bike,
Clicky here