It lets you assign shortcut keys to run any command or imitate another key (i.e. one of media keys if your keyboard miss it). Super simple, but it quickly became my favourite tool.
Example config file:
#(Hotkey0+Hotkey1+...) (delay in seconds:-1 if button release required) (buttonToPress or file to run)
#Apps
VK_LCONTROL+VK_LMENU+Q -1 C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Google Chrome.lnk
VK_LCONTROL+VK_LMENU+W -1 powershell
VK_LCONTROL+VK_LMENU+E -1 C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Sublime Text 3.lnk
VK_LCONTROL+VK_LMENU+R -1 C:\Program Files (x86)\KeePass Password Safe 2\KeePass.exe
#Media
VK_LCONTROL+VK_LMENU+VK_LEFT -1 VK_MEDIA_PREV_TRACK
VK_LCONTROL+VK_LMENU+VK_RIGHT -1 VK_MEDIA_NEXT_TRACK
VK_LCONTROL+VK_LMENU+VK_UP -1 VK_MEDIA_PLAY_PAUSE
VK_LCONTROL+VK_LMENU+VK_DOWN -1 VK_VOLUME_MUTE
VK_LCONTROL+VK_LMENU+VK_OEM_7 0.075 VK_VOLUME_DOWN
VK_LCONTROL+VK_LMENU+VK_OEM_6 0.075 VK_VOLUME_UP