We use SurfPatrol to block access to sites such as porn, violent & offensive, etc. since we are an educational facility. SurfPatrol also does logging, but we never usually look at individual logs unless it is requested, but we do however look at weekly reports to see who's attempting to access blocked sites.
Funny story, a new employee sent an email the other day apologizing because she was trying to access Dick's Sporting Goods website, which is
www.dickssportinggoods.com, but she tried it without the sportinggoods part, so she hit our "Access Denied" page through surf patrol, and was quite embarassed :D