I've always used Noxxic for rotation and WoW Popular for my talent, glyps, and reforging choices. I'd be interesting in hearing what developers refer to. Icy Veins is another good site for learning your class and why to choose certain talents.
icy veins, elitistjerks for dps and healing basics ... sometimes manaflasks (much more detailled and explained guides for each class with description of dependicies ... in times of cataclysm, haven't looked at it since MoP)
Never heard of manaflask, very useful site, information is in depth and explains a lot. Well, I've got four different sites now with up to date MoP class guides.