Among the online LEGO enthusiasts, MOC stands for My Own Creation. It is the quick way to signal that this model constructed from LEGO elements is more than simply a minor variation on a product designed and sold by The LEGO Group. A MOC is expected to be wholly or largely original in design. There are a tremendous number of MOCs from many, many people on display at Kevin Loch's Brickshelf -- http://brickshelf.com/