From bergde­sign:

SuperCal™ is a visual dis­play cal­i­bra­tor capa­ble of mea­sur­ing and cor­rect­ing most con­ven­tional dis­plays, includ­ing LCDs, CRTs and pro­jec­tors. SuperCal doesn’t require any hard­ware mea­sure­ment devices — only your eye­balls — yet it can be much more accu­rate, based on how well you pay atten­tion to what you’re doing.

Highly usable soft­ware cal­i­bra­tion app that gets a long due (Universal) alpha update. If you are seri­ous about your dis­play (no excuse for pho­tog­ra­phers), this one’s a must-have.