Justin Laing recently emailed me to let me know about his SEO sitefinder tool, which uses the ODP and the Internet Archive to find DMOZ listed websites that have not been updated in a while.

Domain Tools also allows you to find expiring domains that will be up at auction soon. You can view their top picks or use the right rail filters on that page to search for DMOZ and Yahoo! Directory listed domains.

Free tools such as DropScout allow you to find expiring high PageRank domains.

You can also look at TDNam for expiring domains, and either use software to filter through those OR sort the results by bids and prices. Some of the domains with many bidders are pure play domainers, but others are old trustworthy sites in need of a good loving owner.