PrcInfo is a compact (87KB) and portable alternative to Task Manager. It's a little on the basic side, and isn't going to compete with Process Explorer or Process Hacker any time soon, but the program has a few interesting features and may be right for some people.
PrcInfo displays a lot of information up-front, for instance. So you don't just get the list of processes: there are also some details on threads (priority and window count) and a list of loaded modules all on the initial display. These aren't implemented as well as they could be (the Modules panel stays unexpectedly blank sometimes) and you can't zoom in on threads to find out more, but it's still a reasonably informative display.
You can easily save the list of running processes, too - just click File > Save and provide a name. This is obviously convenient for creating logs, but might also be useful if you're trying to help a friend with some technical troubles and want to see what's running on their system.
PrcInfo can be customised to support "external viewers", which essentially just means programs which will perform some action on your chosen process or module: scan it for viruses, say. The program comes with support for Dependency Walker, Spy++ and Process Explorer, but you can add whatever you like, and you can then launch those programs from the PrcInfo menus.
And the program also provides a surprising level of low-level control over a few of its options. So if you click File > Create Process, for instance, you don't just get to specify the program you'd like to run, but you can also define how it should be launched: by the CreateProcess or ShellExecute function. Which is interesting, but perhaps a little pointless, as the average user won't care and those who might appreciate this will probably be using Process Explorer or Hacker.