superclown2 - 3:43 pm on Feb 4, 2011 (gmt 0)
If you try buying expired domains with good back links they will cost you a lot of money and links to them will start to decay immediately. This is a valid method if you have deep pockets and are prepared to accept a gamble.
I recently checked up on over a thousand domains that I listed about 18 months ago, all with PR4 or PR5 and all snapped up at domain auctions. I would say that 99% of them were down to PR0 or PR1 at most, but the ones that kept their pagerank had strong .edu backlinks. I suspect that this is because so many pages are posted on .edu sites by people who move on to other things so the backlinks are never checked. Needless to say sites with lots of these links cost lots of dollars!