How many searches?

I was looking at Yahoo's self service ads today. Out of curiosity, I started going through the sign up process, and found that yahoo is sharing some interesting data. When you are trying to choose your keywords, yahoo provides a nice way to see how popular those keywords are. This means you can also see how many searches they are getting for each term. For example, last month there were 30,051,991 for "google" on yahoo. Heck, there were 849 searches for "oren". 676,724 searches for "xbox 360" vs. 333,527 for PS3. It appears that Google just gives you an estimate on how many clicks you will recieve based on your CPC, without actually telling you how many hits that search will get.It seems like this would be highly confidential data; Google's Zeitgeist seems conspicuous in their lack of any qualitative data. I wonder if it's possible to query this information and build a pretty comparison tool based on search volume instead of the usual results returned.