My friend recently got his MacBook zapped by a glass of water. It looks to be a fairly total loss- must have been a short inside of it somewhere (the MagSafe connector doesn't light up when plugged in, and the battery doesn't light up either).
Luckily, I was able to help out some tonight, and it ended up being pretty painless. He brought over his hard drive and I swapped mine out for his. Fortunately for him, the hard drive seemed unaffected, and we were able to make a full backup of it. This is the point where I really enjoy OS X. He didn't have an external hard drive to back up on, so we just plugged in his iPod, reformatted it, and then clicked "restore" within Disk Utility. That way you can basically make mirror the hard drive to another. It worked great, and he should have a clean backup of all of his data for the next time he needs it.
I know through this process you can make a bootable drive, too, although I don't think his iPod was made bootable in our case. But that would be another great way to do it- mirror your hard drive to an external drive and then you can boot right off of that drive like nothing happened. From that point you can use Apple's migration software to pull all of your settings onto a new Mac, or you can just copy that drive again to a different Mac and you're back to where you're started. Nifty stuff.