Once in awhile my skeptical wife will do something to "encourage" me, despite herself. Evidence of her love, I guess. Anyway, while on an outing with a friend of her's in Capitola, she came across a shop that sold Angel cards, thought of me, and bought a set for me.
I've used them in a formal sense only a few times. As mentioned by previous posters, cards like these basically allow your subconscious to "speak", and I found them to be very effective in this regard. I haven't used them much lately as a spread, primarily because I just don't take the time.
What I will do, however, is perform a light shuffle and then pick one card right before a meditation session in the morning. I take this as a sign of what I need to focus on or be aware of for that day. Again, it's basically a tool for communicating with my subconscious. The interesting thing is that sometimes for several days in a row I will pick the same card! I guess that particular message is worth repeating.