I used to have a tape of a thunderstorm in the country with heavy rain.
Now and again you could hear sheep bleating.
I know that it sounds weird but it used to send me off to sleep in minutes.
That must be a personal preference thing; we use our fan in our bedroom all winter, and we keep it so cold in there that most people would be very uncomfortable. I just snuggle down in the blankets (LOTS of blankets). 
I use a fan, or I play a CD of ocean waves. Just steady waves, no seagulls, no music.
Can’t stand the ones that play that bloody awful"heavenly"music.
I’ve been told by more than a few people that using a room fan or the tv is actually more effective and less distracting than sound therapy machines. Isn’t having the tv on in an otherwise dark room distracting? I currently alternate between a couple white noise machines (tried the “nature sounds” type of cd’s…didn’t take) and plain old fashioned counting backwards. I suffer from tinnitus so I have to have some kind of noise in the background as well as doing the counting to ease my mind into sleep.
I had to switch off the iPod sound loop because of a couple of problems… first, the cross-fade was not enough to hide the sound of the transition, and second, the iPod would seemingly just stop for 10 seconds now and then.
I finally caved and got the Marpac 980 ($50 plus shipping). I love it because it provides neutral, even sound that doesn’t loop. Basically it’s a fan enclosed in a shell that prevents it from blowing external air around, which I like because it doesn’t make me cold or dried out like fans do. It sounds like a hairdryer on low speed.
I’ve used this type of two-setting white noise generator to block background noises for a long time. Simple and effective. I suspect thunderstorms, rushing rivers and ocean noises would get me up more often to piss. 
For just noise blockage, wax earplugs are highly effective.
I have this app on my iPad and use it when travelling (just the white/pink/brown noise, but it has tons of other noises too).
At home we just use a fan for white noise.
I really like this one from Bed Bath and Beyond. I’ve had it for years, but now that I reread the original post, it probably has the same sounds as the one he has already tried.
Yeah, I have the app that Uncle S. recommended. I like it, and I don’t hear a loop.