Let's see. 30 minutes before work. 4 hours of my work would be spent online, be it for work or "work." Then I get home and there's another potential... hmm. 7pm average home time... 5 hours 'til midnight... 1 hour after... yeah, I'd say about 6 hours. So that's 10:30 out of my 24 hours alive each day. I have access to the internet for 21-22 hours of my day - two to three hours a day is spent travelling to and from work. 6 hours is spent sleeping. So realistically I guess I'm able to jump online for up to 16 hours a day. Whoop.

EDIT: Maximum 20 hours a day in the weekend, but there's no way I'm doing that. I'd say I spend about half of my weekend online, the other half sleeping, watching TV etc.