I'll interrupt to say I really like Moby: Ambient, but I actually wouldn't call it strictly ambient as it is more beat driven than most ambient releases. It's considerably more laid back then stuff like Play, 18 or Everything's Wrong, which might be a good one to check out if you like 18 and Play. Not meaning to speak against Ambient as I really like it, maybe even better than the others mentioned, but I'd suggest Everything is Wrong is more similar to those other two than Ambient.