I usually have tabs for the following sites open whenever I'm using a browser:
Google News
Gmail
Calgarypuck and a few other forums
Twitter
I also use
Flipboard on my iPad at least once daily to check the day's top items from TechCrunch, Mashable, and Reddit. I tend not to browse those sites from a PC, though.
Beyond those, I check Facebook and Google+ daily, but I only really visit those sites if I either want to post something or I receive a notification.