IIS log size–under your control!
Logging the traffic coming into a website is very important, but on a busy site, the log can generates many gigabytes of data every day, making it hard to control disk-space and prevent the drives from filling up.
As a result, many users turn off logging completely, although this can make it impossible to track down suspicious or illegal activity. The good news is that there are multiple ways to keep a tight leash on log size without turning logging off. The following article by Jim Van De Erve discusses several methods, from simple disk compression to a 3rd party tool that trims the logs automatically.