UPDATE: nDo 2 is out, do yourself a favor and buy it at http://quixel.se/ndo!
I just want to introduce you to a great (and free!) tool-set for quickly designing normal maps without ever leaving Photoshop. nDo is a melting pot of normal creation techniques created by my friend and co-worker Teddy Bergsman.
Sculpt using custom brushes, create volumes from selections, paths or layers, apply filters, generate complexly multifaceted normal maps from height or photographs, rotate and transform without biasing normal.