In contrast, I have installed and test-driven RescueTime 3 times over the years.

One reason I like TagTime better is that unlike RescueTime, it TagTime does not cancel shutdown if I forget to stop it before I try to shut down my OS X machine.

Another reason I like it is that unlike RescueTime, it does not hide my data from me: TagTime has a file, called richard.log where "richard" is whatever your user name is, with all my data in it in a very simple format.