How can I obtain older versions of Xcode? How can I obtain older versions of Xcode?  

Is there a way that I can freely download a version that only requires OS X 10.6.8? So far this is all I've found on the matter; but, when I click the 'download Xcode 3' link, it simply brings up the page for downloading version 4.
You can download older versions of Xcode here after you've logged into the dev center.

Uncheck all of the options except "Developer Tools" in the Categories section on the left side of the page. Every version of Xcode back to version 1.0 in 2003 is available there.