I have no idea what my total average speed is, but, like most of you, it depends on the company and the situation! I race, so my speeds tend to be up there.

The Tuesday night ride from my team's sponsor shop averaged 24.5 mph on rolling terrain (it's prettymuch an all-out hammerfest) last week. I felt like superwoman after keeping up with that one...
On a 30-40 mile solo recovery ride, I'll usually just spin @ around 17-18mph

Most of the time, I'm somewhere in the middle.