The times I've looked, I wasn't able to find one where Angels were more than a subclass or bit role played out by the GM. I've always held a fascination for them, and the heavy focus on Angel mythos in this current season of Supernatural validates my belief that this concept can be fleshed out appropriately; angel hierarchy (seraph, cherub, ophan, hasmal, virtues, dominions, etc.), war and rebellion, friction between factions, relations with humans (nephalim and influence), the Fallen, identity crises (questioning beliefs and rank), spiritual evolution... I won't go on, but hopefully this shows how much I agree with you. If you have something up your sleeve and are serious about seeing it through, I encourage you to put it out there. Interest checks can serve as classifieds for Co-GM's, too :)