For any internet-obsessed person....
...when you close off the internet and get an awful empty feeling
...when you have more forum friends than you do in real life
...when you get up at 3am to go to the loo, and on the way back, check for new posts
...when you can't talk to your relatives because they don't have a modem
...when you automatically assume that EVERYBODY knows about an interesting thread you read the other day and are baffled when they have no idea what you're on about
...when you're so used to people not knowing the tone of your voice on the forums that you give up using sarcasm altogether
Forums are definitely taking over your life when:
a) A thread like this is posted

You are actually interested that a thread about forum-life-domination is posted
c) There are 7 pages of replies in a short space of time to this thread
d) You can identify with half the traits that forum addiction instigate
I think that on the original list, I had about 2 or so out of 10... but I'm "blessed" with a terrible computer which decides not to work some days, so quite often it's more trouble than it's worth to come on here. But at times I have found myself losing an hour or more in the cafe...