Up until February 2012, the only way you could get the Command Line Tools required for web development was via the full Xcode package, which is almost 2 GB in size. Since then, Apple started offering the Command Line Tools (CLT) as a separate, much smaller download (~118MB), which benefits those who don’t plan on writing Mac or iOS apps. There is also a third-party option, the osx-gcc-installer by Kenneth Reitz, that supports both Snow Leopard and Lion. However, it is not updated as often as the official Apple tools, and I personally ran into issues with it on Lion.