Get a decent speaker set + amplifier + MP3 player.
1) Download and install
Goldwave
2) Create a new file. Length...I don't know, 5 minutes maybe? 1 might be good, though I'm good at finding repetitive patterns in white noise if a short sample is played repeatedly.
3) Tool menu -> Expression evaluator
4) Noise -> Brown or White. I prefer Brown noise.
5) Encode to MP3 with
LAME;
Razorlame is a good GUI. However, you can use this commandline to get highest quality: -q 0 --replaygain-accurate -b 320
6) Set to loop on your MP3 player.
As for power consumption, I don't know what a speaker set and amp can draw. But if you go for low power, you can't get very much sound.
(Or maybe buy a
Tornado Fan. ~16W draw.

)
For fun, boost the bass on your speakers, and do this:
Effect -> Filter -> Lowpass, Initial Cutoff = 200 Hz
Originally posted by: Throwmeabone
earplugs?
That, plus
this, plus
this. (Vibrating portion runs off a wall wart, so if the power is out when you need to wake up, the clock will keep time, but it won't be able to wake you.)