Google "Suggest Tool" is Now in BETA, Very Nice Tool from Google
I have been using this tool for a while. It is now in beta, and you must check it out. It is Called google suggest. As you start typing in search terms it displays possible other terms, and how many results arein the google universe right below. Very slick!
It is designed to help you select search terms, but it can be used by adwords professionals if they look at the tool from a different perspective
You can use this tool to help you in your keyword list building process. I really like this google tool for several reasons. It can help you think of other search terms for your adwords campaigns (these other terms do not always show up in the suggestion tool with adwords).
You will want to use this tool. Give it a run here: http://www.google.com/webhp?complete=1&hl=en
Seethe FAQ section here for google select: http://labs.google.com/suggest/faq.html