If you're into the homebrew scene and you're not playing Pocket Physics, you should be. Not only is the game (or non-game, depending on how you view it) incredibly charming, but it also has a lot of great features. Take, for example, the ability to save your creations.
As you may or may not know, we're big fans of user-created content, so we're always curious about what kinds of levels other people are making. Now, though, we don't have to just settle for curiosity. Thanks to return1's Pocket Physics dump, players of the homebrew can both upload their creations and download other users' content conveniently.
There are already seventy-five files available at the site, so you'll definitely be able to feed any physics-engine addictions that you may be suffering from.
[Via NDS Homebrew]