Knowing what keywords people are typing is an important part of search engine optimization. I use a number of different keyword tools including Wordtracker but recently started to use a new keyword software program called Keyword Discovery and Im very impressed.
Its probably the best program out there to discover what keywords users are typing in the search engines and it helps you to come up with many additional keywords including mis-spellings of words. Keyword research should be part of every online law firm web site marketing campaign.