PokerMuck is a GNU GPL online poker utility for the Windows platform maintained by Piero Toffanin. The program offers a muck viewer and an advanced HUD. It currently supports Hold'em games (cash and tournament) for several poker clients. It can be easily extended to support more clients and game modes.
Windows Installer: Download (might be broken, please compile from source code using Visual Studio if you have errors).
Check the website for more information: https://pierotofy.github.io/pokermuck/