||How Does Open Source Software Stack Up on the Mac?|
Though it is not OSS, a development IDE I use which is pretty much ignored by the Mac community is SlickEdit (http://www.slickedit.com/). I've been using this tool for over 5 years now (first on Windows and now on MacOS X) to do embedded cross-development as well as platform independent code. It is able to read Xcode project files and can generate Unix-baed make files. SlickEdit's variable tagging is the best I have seen (Xcode has nothing even close yet).