In a way I'd say no... but actually I think my life and most conveniences are built around "being online".
I don't buy magazines but I read articles on websites. I don't read a newspaper but I visit CNN.com (which isn't even on cable tv anymore). I only have my tv around for watching DVD's, thus I download series. It's how online life becomes a 'weird" integral part of living.
Yes, I could do a day without being online, but that would mean that I don't have a clue what's going on... unless I buy a newspaper (which has yesterdays news). I know how it was back when I had to visit a record store and order a cd and wait for it, for about 3 weeks, it's something I don't want anymore, because I know that iTunes gets me that album in 5 minutes.
I think I could even state that if I were to lock myself out for a day, I'm locking myself out of "my world" for a day on purpose. It's where I have more friends on IM, than contacts in my phone, I'm being sent an email rather than a letter for business and stuff like that, which makes it a totally impractical situation to just tell myself "today I'm offline". I did have those days, but I should add... I do have to have some plan. It's like "how much time do you spend on a computer"... a lot, because I don't have the luxury of having a piano, a console, a typewriter, a decent sketching tool and a extensive physical movie library around... internet as a tool is the same.