OpenMacGrid is a computing grid built up entirely of Macs, and open to Mac-using scientists everywhere. OpenMacGrid is based on Apple's Xgrid technology, which comes pre-installed with every copy of Mac OS X 10.4 (or later). The potential of Xgrid has always been obvious, but until now, it has never been fully realized. OpenMacGrid will change that, by bringing the spare cycles of Mac users, together with the computational requirements of Mac researchers.