Here at BMON we use the moz.com toolset quite frequently, and consider it well worth the subscription fee. There are free tools there too, which will be of interest to anyone in online marketing, including the excellent Keyword Explorer. This has a new feature which you’ll like to explore: the ability to list search terms for which any given site is ranking. Using this, you can see the most important terms that their database thinks you rank for, and compare your profile to competitors. But read their introduction for more.