TortoiseHg DVCS
TortoiseHg is a graphical tool for managing Hg repositories. It is modeled on a number of 'Tortoisexxx' packages for other CVS and DVCS systems, but is independent of them. One of the differences of the Hg version over some of the others is that it actually available for both Windows and Linux. It is one of the main reasons for using Hg rather than Git since it is transparently supported across both platforms, while the TortoiseGit version only supports Windows.
In addition to the graphical workbench, it also integrates into the windows file explorer, and the nautilus file manager on linux. This provides additional tools for managing the file structure outside of Eclipse, which has it's own restrictions on non-managed files.
TortoiseHg provides the main advantage of Hg over Git.