I used to create packages for a couple of open source projects for the openSUSE Linux distribution. They have this really nice build service running on build.opensuse.org, on which you can – despite of its name – also build packages for other Linux distributions like Fedora, Gentoo or Debian.
While the web-based interface of the service is nice, some configurations and local builds require their command line client osc though, which is python-based and works similar to subversion. This client however was only packaged for the main distros the build service itself supports, but was unavailable for others like f.e. Mac OS X, so I created a MacPort for it today (installable via sudo port install osc).
Of course local Linux builds are not possible with it, as we’re missing the complete environment, but I think its still useful for maintaining and managing remote builds on the service itself. Have fun with it!