ive had 3 360's. first one kept crashing, second one i returned for the hell of it to the shop cos it had trouble reading the odd disk.
third one was fine till last month when i got the 3 red rings. but as it was out of warranty i just ripped it appart, ripped the heatsinks off it, cleaned off the crappy thermal paste that was on it, and put some arctic silver 5 on. slapped it back together and voila, a month later and still no problems
infact my friends launch day console also died recently, again waaaaaaaaay out of warranty. he asked me what he could do, i told him what i did and also said that wrapping it up in a towel for like an hour or so sometimes works.
he searched it on the net, figured he'd try it as he hasnt got anythin to loose. wrapped it in a towel, left it turned on for an hour, turned it off and unwrapped it, let it cool down for a couple of hours and again voila!

its been workin fine ever since lol
I know we shouldnt have to do this to a console to get it working but honestly guys, if you do get the 3 red rings and its out of warranty, why not try some of these fixes? a lot of the time they do work and your not gonna loose anythin if they dont