This is a module that will truncate the ad_statistics table on cron.
Why the heck would I want to do that?
1) You care about the size of your database
The ad_statistics table records way too much information about ads, it records so much information that on some of my sites this one table is more than 500x larger than the entire rest of my site!
2) You do not need to keep track of your own ad statistics
When I'm using the ad module, I'm usually using it to serve up ads from other sources that do their own statistics tracking, all I need this module for is management of the ad content, and display options on my site.
Until this issue is resolved, I'll be using this module instead.