When I tell people that I'm now working for myself at home, the first reaction is usually "wow, that takes a lot of self discipline". True, it does. There's no replacement for healthy self discipline. However, as with most things in life, there are levels of gray here. I always seek ways to improve.
I found this great tool that helps me keep going. It's called RescueTime. It's a small little gizmo that sits on my machine and monitors what I'm doing. I can then log into the RescueTime web site, see a graph that shows how much I've worked and when. It logs tasks according to the process being executed or the web site being visited. Monitoring URLs is important since many applications are online today. I can then tag the activities with tags like "work", "fun", etc., and get a summary of my activities according to my tags.
So, if you tend to lose track of time reading your RSS feeds or in IM chats, this will give you the required feedback to get back on track. It's like a mirror, providing silent, yet deadly honest, feedback.
RescueTime supports PC and Mac, and is currently in private beta.