By now you should know I love analytics and conversion tracking and if you run any kind of search marketing campaign you should too!
There are tons of stats and analytics out there but none of the free ones match the details of complete search marketing of Google Analytics. GA used to allow only 5 profiles per account but tonight have increased that to 10. Not sure what to do with 10, you can use them to track different levels and portions of your site, to give you even more detailed analytics. The only catch is if you have more then one adwords account, you will need a seperate analytics account.
If you are only intersted in Natural Search Stats then you should check out Enquisite