Mac: There are plenty of to-do list managers out there, but TaskBadges keeps things simple by integrating a plain text file list with a handy notification badge to keep you up to date on what's left on your plan.
TaskBadge's approach is limited in its scope, but the ease of use might outweigh the lack of features for some. Check off a finished project from the text file, save it, and the counter drops, always showing the number of items still left on your list. As long as you keep the program running, you can have as many different lists as you need. All you need to get started is to start editing one of the sample lists included in the download, or you can import lists you've already made.
It's still in beta, but considering the simplicity of it and the fact it's free, it doesn't seem to have any major bugs. It does seem to struggle to keep up to date if you try placing the file in the dock, but if you save it on the desktop it updates right away.