EventGhost

OS: Windows
EventGhost is a must have tool to get a real home cinema experience with Media Center software. At its base level it allows you to remap keys to other keys, nothing that special but when you through in its support for a wide range of usb remotes then it becomes so much more powerful. I personally have a gigabyte remote and I spent ages looking into keymap software trying to find some that it would work with and EventGhost is the only such software I found, it allowed me to not only control every aspect of XBMC but also allowed me to change system volume with an OSD showing current volume and even terminate XBMC when it stopped responding and restart it.
Its features dont just stop there though. It also has window and mouse controls, sound, display and registry controls and more importantly the ability to run external programs and python scripts/commands. EventGhost also boasts a wide range of plugins too, these include support for many popular remote recievers, control scripts for many programs, external equipment and even plugins that watch process creatation. All of these features complimented with some basic logic mean that there isnt much you cannot do with EventGhost and thats why its my top Key Remapper software.
Visit EventGhost's Site - Visit EventGhost's Download Page

AutoHotkey

OS: Windows
AutoHotkey is another one of my favourite programs and a powerful one at that. It is a programming lanuage at its very base but provided with detailed and comprehensive documents its very easy to use and even non programmers should be able to use it quite easily. Its not got as good support for remotes as EventGhost but what it lacks it more than makes up for with its huge range of commands that will suit almost any hotkey related program and even some that dont even use hotkeys. Also it has the ability to create an exe from your scripts meaning unlike ExeventGhost you can distrobute your software and the user doesnt have to have AutoHotkey installed for it to work. All in all Autohotkey is very functional and useful and probally better suited than EventGhost for some things but if you own a remote EventGhost cannot be beaten. Visit AutHotkey's Site - Visit AutHotkey's Download Page