It depends on what day it is, what else I'm doing that day, how active other places are, and if I want to make a conscious effort to be here. Some days I only pop in for ten minutes at most because that's all I have time for, unfortunately. Other days, though, I could spend a solid hour poking around the site, reading every thread that catches my eye. Then there are the days where I have nothing to really do but sit at the computer, and those days I'm here and there every few minutes to add up to a significant amount of time.
On average, I'd say that I'm here for around an hour a day. Maybe two if I'm feeling generous.