I\'ve googled the hell out of it, and it seems like there is no way to install gcc on OS X without installing Xcode (which takes at leats 1.5GB of space). All I need is gcc
The first thing you want to try is called Pacifist - what Pacifist lets you do is to open a large package (such as XCode) and to access parts of it directly. I'm pretty sure you'll be able to find a smaller package inside the XCode package that just has gcc.
HOWEVER it's not clear to me that this is the best route. If you are planning to do Cocoa or Carbon developing I strongly suggest installing the entire package because you will need all the documentation and headers. If you're only planning on doing command-line stuff, you still may find you need to poke around inside XCode to identify all the packages you will need - things such as libraries, headers, man pages and so on.
All in all you're probably still better off installing the whole thing - if HD space is really tight (because you're on a tiny old iMac for example) then look at tools like Monolingual - Monolingual removes all the international support from all the various OS X applications, which can easily reduce the size of an application by 50%.