Process Hacker is an open source replacement not only for the built-in Windows Task Manager, but also for the popular Process Explorer tool. Process Hacker implements many of the same features that Process Explorer has for examining local processes, and adds a number of unique capabilities that are especially useful when examining an infected system or analyzing malware.
Selecting Properties gives you several tabs. One of the most useful ones is Memory, which lets you the ability to view contents of the process' memory, extract strings, search based on regular expressions and even modify memory contents.
Other capabilities of Process Hacker include the ability to locate some hidden processes, inject a DLL into a process, create a service, locate file handles and DLLs, and many others. The best way to become familiar with the tool is to experiment with it. Give it a try, then be sure to share with others what you have learned.