This is probably the top question I get asked, so I thought I'd list my time out here:
-Twitter: I check in a couple times a day, and scroll maybe the first page of tweets in my newsfeed. I post tweets more frequently, but those take maybe two minutes to write. - Total: app. one hour per day
-Facebook: Err...I spend a lot of time on here On days when I have to help the Jaycee groups I spend an extra hour - probably two hours a night and an hour spread across the day.
-Blogging/Reading Blogs: I don't blog as often as I should (guilty!), but I do spend a lot of time reading my favorite blogs (Frugal Dad, Retire at 40, Sustainablog, Construction Marketing Ideas, Seth Godin's Blog, Blog Maverick/Mark Cuban) - probably an hour a day total. If I write something for my blog make that an hour and a half.
-Ravelry/Craftster: I peruse at my leisure. I will go weeks without going on at all, and then stay on for hours a day. It all depends on that weeks content or if I'm looking for something. - probably fifteen minutes a day
-Email: I still spend a LOT of time on email - I run the mailing lists for my USGenWeb sites, interact with people on the Canadian ones and am an the National Advisory Board for USGenWeb - which translates into a ton of email. I also get a lot of newsletters sent to me because I'm terrible about checking websites. - Total spent across the day, 3 hours across 3 email accounts.
-Google: I've set up alerts for my name and my maiden name to see what comes up. Sometimes I have to play defense, but most of the time its a pleasant surprise to see my name in the news (even if its not me). - total spent: 10 minutes a day
-Flickr: I still post pics when I have time, but rarely do I do it when its not associated with Ravelry somehow. - maybe ten minutes or less each week
That being said, its not the majority of my day spent on the SM circuit. I still make plenty of time for working, knitting, eating and working out.
Anyway, what reminded me of this was the latest batch of emails I had received expressing wonder about how much time it took to do this and then there was a beautifully written piece at Museum 2.0 about the topic of how much time they spend doing things and what they recommend for time crunched museum peeps.