Developer Mehmed Ali Caliskan from Turkey has a blog post up where he demonstrates how to get a process list of running applications with Delphi Firemonkey on Win32 and Mac OSX. His code is from an earlier version of Delphi but it should convert forward to XE6 without many changes. He created a custom class to place his functions in called TPlatformExtensions. The two procedures demonstrated in the blog post are called GetRunningAplications() and there is one for Windows and one for Mac. They fill a TStringList with a list of the running applications on the machine. The source code is available for free on Google Code and includes the utility function units and a demo application demonstrating their usage. Other functions contained within the utility class are GetSystemFonts, GetTextMetrics, and ShellOpen. The font functions allow you to list the fonts on the system and then get various text size metrics about each font. The code is in Object Pascal so it will probably work in AppMethod as well but obviously it is not for IOS or Android.
Check out the full blog post with complete explanation for getting the process list on both platforms.
Or check out the source code for the TPlatformExtensions class on Google Code.