Mine comes with me everywhere, when at work, I use it for news, twitter, email and a bit of "outside of work" browsing (have full access at work, so not needed really).
Outside of work, I keep working, my emails are pushed, I VPN then RDP/VNC to servers, unlock accounts etc...
Then, on the weekend or on the bus, I use it for music/video and news.
I love reading on it, the kindle app is good, can't wait for iBooks (provided it is cheaper than kindle).
I would say, out of the 17+ hours a day I am awake, I use it 14+, it sits on the charger at home and work though.