A link on e38.org will take you to:
http://www.bimmerboard.com/forums/e38/
Which is the best forum for the car. Tons and tons of traffic and info.
It's a great car if you can bear the maintenance. The interior space is superior to a 5 series if you want/need it. We've put about 85k miles on ours (now at 191k) and it is still a fantastic car.
Maintenance costs are significant. There are several well known, mileage related failures - plenty of info on the above sites if you want to DIY or you will be well armed on a visit to the mechanic or $tealer.
Don't pay too much for one! They are unbelievably cheap to buy used - due to the maintenance costs which scare most folks away. But anyone on this board already knows about high maintenance costs and should not be shocked!
best,
Dave
99 R11S
97 740iL