Redmine (redmine.org) is a free, open source alternative to basecamp/trac written in rails. It's great for tracking issues for your own projects, but especially useful to small teams. There are numerous plugins available to meet individual needs (scheduling, time tracking, etc).
Redmine is nice, though I think I prefer the little things that Backpack gives you that's tailored towards personal/team use and the better UX. It's only $7 a month if you use the (unadvertised) "solo" plan, which you can upgrade to after you sign up for a free account. (I hope jasonfried doesn't mind.)
I actually don't use anything. I find it's easier to follow your instinct and do what you want rather than sort out your life. Then, whatever you've been doing that's not productive, you force yourself to stop doing.
