I spend some time on the Internet. mostly I "lurk", but there are a few places I post from time to time. 

• alt.callahans - a newsgroup loosely modeled on the bar from the Spider Robinson stories 
• comp.database.ingres - I use this in my work, although less than I used to (change in job responsibilities).
• A variety of MS Windows related groups. This is both professional and personal, since I use Windows and MS products both at work and at home.