I've been looking for some good "white noise" or "pink noise" audio
files for some time, preferably free.  I've even looked at a few
programs that are supposed to produce such noise, but they've all been
unsatisfactory.  

What I'd really like, and haven't been able to find
is the engine noise/ambient noise from Star Trek: The Next Generation.
 Like when they are in their quarters you'll hear in the background a
lowish hum.  Where can I find those sounds (preferably for free, but
if not for cheapest) without going and ripping them myself from the
show?

don't know where the star trek sound is, but I use a great white/pink
noise generator that I downloaded for free at www.blackholemedia.com
--it's for a mac.

I do know that the Star Trek: Generations soundtrack has a soundfx
track at the end -- one of those tracks has a long recording of the
bridge ambient sounds right before the crash at the end... you might
be able to loop it.

Thanks a ton for the comment, I'll check those things out.  I have a
mac so that'd be perfect.

There is an audio testing cd called "Food for Woofers" that has a
track called "Star Trek"
(://www.google.com/search?q=%22food+for+woofers%22+%22star+trek%22).
 This _might_ be the sound you are looking for, but I'm not sure and
haven't been able to track down a sample.  If it is the right sound
it's still only 15 seconds long, but you can get a hold of it you can
probably bring it into an audio editing program and first smooth out
the ends to make it loopable and then copy and paste it until you have
your desired length.  I've used audacity (free, at
http://audacity.sourceforge.net/, and there's a mac version) to do
this with some success.