So far, the places we've landed are all within our solar system. But this list keeps on getting longer, and the compiled image keeps getting wider. I love the future.
The Distant Horizons graphic was originally designed by Mike Malaska, and was most recently updated by Micheil Straathof to include Philae landing on Comet 67P/Churyumov-Gerasimenko. The full list of image credits to the people and organizations that made it possible are embedded in the image. You can download additional sizes of the image at Malaska's Flickr account.
While we've gone through the list of every planet that has ever been occupied by robots before, it's pretty awesome to see them all displayed in one, beautiful graphic. Even though the list of landers and their destinations is far smaller than all the robotic probes we've sent out exploring our solar system, it's still adding up to a downright impressive number of locations for a bunch of fragile, squishy creatures to send explorers.
Technically, this doesn't include Deep Impact firing the impactor-probe into comet Tempel 1, but as that was the exploration equivalent of firing a bullet at a comet and not a nice, soft landing (or, in Philae's case, bouncing yoga) I can forgive the omission.
Update: They also forgot NEAR Shoemaker landing on asteroid Eros. Assumably that's because the orbiter wasn't designed as a lander, although it did manage to soft-land and survive for a few weeks anyway.