Of course any tool can only access these stats as often as 15 minutes but the authors are well aware of that fact and none of these tools will get you in trouble with Google because of that.
If, however, you’re browsing content most of the time, and your tool of choice is the Firefox Internet browser, there’s an extension for this program that allows you to view the stats in your status bar.
Again, this software is aware of Google’s 15 minute rule and enforces its usage, 15 minutes being the minimum time between updates. The Google AdSense notifier for Firefox can be obtained from http://code.mincus.com/?p=3
There is also a program called Golden Keywords out there that helps you in getting the best keywords for your site. It’s really efficient and very easy to use. It does come with a price tag though, it costs $49.95 and it can be obtained from http://www.regnow.com/softsell/nph-softsell.cgi?item=8616-2