Xcode, GCC, and Homebrew. Looks good - Apple provides a bare-bones GCC package with all frameworks, so you no longer need to load the monster installer from the AppStore, but can make do with a 170 MB package and still use Homebrew to compile open source OSX programs (at least as long as they don't use explicit XCode features). Especially if your own programming takes place in other IDEs and with other languages, it's quite nice to be able to do without the 8 GB that an installed XCode occupies. I'm seriously considering whether I should also give my Air this slimming cure.