Absolutely nothing because I am generic and boring (when it comes t o the desktop). Heck, the only 3 things on my desktop are the bin, steam, and roller coaster tycoon. None of which I ever click from there anyway. Used to use rocketdock but I uninstalled it at some point for reasons I can't remember.
I use rainmeter and hide all of the other stuff from the desktop. I have the taskbar and a little rainmeter side panel and that's it. I don't use anything for OS X -> I just hide the dock at the left hand side and choose a nice wallpaper ;D