Leasehunter.com seems to be the most comprehensive and best that I've seen/used previously. I would advise to act quickly upon something you are interested in with $$$$ in hand.
^^^Agree with DQ. I hunt and manage a large lease so we got lots of hunters. Even though its a good place there will still be some turnover from time to time so I have some experience filling spots. I have used several websites and even though a blind hog will eventually find an acorn, it has been my experience that most of them are very ineffective. Not at all the case with leasehunter.com. Having said that, it is still a long shot finding a lease through them. You should use every resource you can muster cause a good lease is hard to find. I will also suggest craigslist. Lots of folks will tell you to stay away from them and I assume you have to be careful but there is(at least used to be) a lot of activity on there. I am not on facebook at all but I assume its kinda like craigslist in that theres a lot of activity but once again be cautious.
Understand my advise is from looking for hunters and not looking for leases so im not certain it works both ways. I also encourage anyone looking for lease to go back and look at old threads on here. There have been some recent ones offering good advice on looking for lease.
And good luck!