Depends on what you want to do with it. If you aren't ever going to take it to the snow, take it off road, or use it as such, then I would just keep it 2wd. You have to look at your needs and wants and go from there.
As for lift kits, search. There's a sticky at the top of the 3rd gen forum on lift kit info. Start there.
I'm going to make an argument for locking your 2wd. I think we're getting into semantics a little bit here with the term "off-roading." To me, off-roading does not equate to rock crawling - which is something I would consider EXTREME off-roading. I have a pretty-much stock 2000 Limited 2wd as well, and I would NEVER attempt rock crawling in it. My definition of off-roading... Are you on a road? If not, in IMHO you're off-roading. I do a lot of camping and a lot of duck hunting. I find myself on dirt "roads" that are nothing more than ruts that have been traveled enough so you can see what line the last guy used to get from point a to point b. And I will also bounce across an overgrown pasture once in awhile. I've done this both in wet and dry conditions. I am planning on a locker some day, but I can tell you that a stock 2wd 4runner will absolutley surprise you on it's capabilities. Lock it, and I can only imagine what it can do. Spend some time on COB's build thread. His is not only a 2wd, but also a 4 cylinder. EXTREMELY inspiring and shows you what you can do with a 2wd.
