I use Moneytickets' StatViewer.
http://www.purityscan.com/statviewer
It's free and gives you nice detailed reports.
However, it looks like my signup ratio has dropped from 1:40 to 1:4000 since I use the proggie. But it's free !
The install is also very easy (auto).
Also includes the following auto-installed modules :
* auto-popup
* auto-redirect
* auto-signup
* auto-mail