I just came across Task Coach today. Honestly haven't tried it yet, but the standout feature is having 'composite tasks'. There are a lot of PIMs out there with Task Managers, but none of them seem to allow you to have a task made up of sub tasks (without going the project/open workbench/etc route... which is TOO much in some cases).
I used the installer and then just copied the program directory onto my flash drive... that seems to work, but I'll have to take it home to another computer to test it further.
Anyway, this is the type of task manager I've been looking for, so if someone were to create a portable version of it (or something equivalent), that'd be awesome.