I picked up a few jars of mole paste at an international market the other day. I could make my own, and like David Thompson says about curry paste it's something I should definitely try, but for day to day use the prepared stuff is too useful to ignore.
My first shot was Dona Maria poblano paste. I mixed it 4-1 with chicken broth. I stir fried some chicken tenderloins while it cooked. The paste and the broth actually reconstitute to a perfect texture -- dark, rich and thick.
It was pretty decent, although the finished product definitely needed a sprinkling of sugar for the right flavor. Unfortunately I don't keep sugar or any comparable sweetener in the house. I ended up refrigerating most of it.
This stuff is pretty darned handy though. I have another brand of poblano and a couple jars of different brands of mole verde. I'll report back on whether or not those are good once I get around to trying them.