The internet can definitely be addicting and suck away at your time and your life. But so can hundreds of other activities. But yes excessive internet use has been the biggest problem for me, particularly in feeling overwhelmed by the amount of choices and falling prey to distracting activities when I needed to get more productive things done, either on the internet or off it.
But I've improved my behavior in recent months. The key I've found is finding ways to motivate yourself to be more disciplined in your internet use. Reading blogs like
Zen Habits has helped. Leo Babauta, the blog's author and his guest posters have a number of good articles to read about controlling your internet use, as well as a number of other useful lifestyle posts.
Also creating some form of self imposed monitoring has helped me as well, particularly if I am using the computer to get work done. Just as monitoring your progress if your trying to achieve a goal like weight loss can be useful and motivational, so can monitoring your internet use. The easiest and most effective tool I've used so far is
RescueTime. It monitors which websites and applications I use, then assigns productivity ratings to them, graphs out the results and gives me an efficiency score. I run it at times when I want to be productive and limit distracting and time wasting activities. I also set goals on the site for how much time I want to spend on productive activities and a goal limit for how much is spent on distracting time. It doesn't block sites or limit me in any way and I can turn it off whenever I want. But if I want to keep most of my internet use at a particular time productive, having the game-like positive reinforcement of trying to raise my efficiency score and meet my daily time goals really helps motivate me.
Also, say you have specific offline social anxiety related goals that you want to do to, if you've left the app running, you can log them in after you return to your computer and assign them a productivity rating to boost your score for the day.
It's not for everyone, but it's definitely helped me control my internet use.