I dunno, you could check here and see if there are any domains that are going to be dropped tomorrow and possibly put a backorder on them or something. . .
If I found like a PR2 domain. Then buy it. Would people be interested in buying it? Is this a good way to do business?
If it has a lot of backlinks, then people would probably consider buying it. . . If its just a PR2 with not many backlinks, you will get something for it, but not a lot.
As far as I know the PR will drop in the next update. If you were to develop it right away and build new links you may be able to obtain the PR. Dont quote me exactly on this though.