I have been doing for a bit of time and I have come across a couple tools that I recommend everyone into SEO and Affiliate Marketing uses. Between these two extermely good tools you will have as close as you can data that the search engines use themselves – they are better 10x than anything else you can use on the web for checking links
Majestic SEO – http://www.majesticseo.com
Syntryx – http://www.syntryx.com
If you are at all good with data blend these together. Majestic has extremely good crawl data and Syntryx can do priority crawls and is simply the best for sniffing out affiliate patterns for competitive research
Anyone else use any tools they like and what are you reasons?