Finally something I can comment on.
I have bought a few salvage vehicles over the past few years, including a couple of jeeps.
First thing is you need to really know what your looking at, for example if the jeep is hit in the drivers side front, 9 times out of 10 the drive shaft got pushed back and broke the transfer case.
I could go on, but there's lots of little things to look out for.
If your not planning on licensing it, local salvage laws don't matter.
However if you are, research what you need to do to register it after completition.
In New York (where I live) it's not a huge pain after you've done it a few times, you basically just need to keep all of your reciepts for the repair (body panels, t case, lift), whatever you put into it, and make a (special) inspection appointment. They look it over, and you have a title in about a week.
Pennsylvania is even easier, and inspection station can look it over, sign off, and you just mail the paperwork in.
One side note, here in NY they passed a law that you cannot replace air bags with bags from a salvage yard, they must be new (reciept required), so needless to say, I stay away from anything with blown air bags.
Here's the website I use, the Buffalo NY salvage auction happens to be about 2 miles from my office.