My personal favourites are: Yahoo site explorer: https://siteexplorer.search.yahoo.com/mysites MajesticSEO: http://www.majesticseo.com/ LinkDiagnosis (uses the Yahoo api): http://linkdiagnosis.com/ SEOMoz Linkscape: http://www.seomoz.org/linkscape SEOMoz open site explorer: http://www.opensiteexplorer.org/ Have fun
There are many. I use http://www.searchbliss.com/seo-tools/popularity.asp because I control it, so I know how it works.
backlink watch is good except they have annoying ads and they constantly are overloaded...but they are the best free tool I've used to date.
The SEO Spy glass is slow but very, very good and the only think you can't do in the free version is save reports. http://www.link-assistant.com/seo-spyglass/
If you want a good paid software, try SEO Elite. To get 65% off just set up your own clickbank affiliate account and then buy it through your own link! You may want to use your spouse's credit card though...
Just bookmarked this page and all the sites that were recommended. Also, I've got a subscription to SEOmoz and recommend it and their tools. Open Site Explorer is hot.
I use https://siteexplorer.search.yahoo.com/ it and lot of another free tools on internet that can be used if you like.