Banachek's Psychokinetic Time, is practically impromptu, especially if you wear a watch yourself.
I've done a few feats of contact reading at work and among friends, these techniques are taught in Psychophysiological Thought Reading. At work i've had somebody think of a tool. You could couple contact reading to appear like your using non-contact reading as well, just use your imagination and performing skills.
You could use cold reading techniques as well to give an impromptu reading or to improve any of your other effects. Blitzmagic mentioned Luke Jermay's Building Blocks, there is an effect in there that involves an aura reading. That's a good way to bring up your cold reading skills. Also in Luke Jermay's Seven Deceptions he has an effect called "Twisted Palm" where the spectator actually sees the lines on his or her palm move and twist, use this effect with cold reading and you have a beautiful impromptu effect.
A strange garden from Luke jermay building blocks use the same principle from the twisting palm effect, You take a leave and ask them to look at it, and they will see two pattern on it, the magician then reveal wich pattern they saw, You can make them see different pattern, I dont know if you can make them see cards, but its complex because you are doing somewhat a mental force for the desing.
It's great, whenever you are walking outside talking with people and you get to find a leave on the groud, it's terrific, I love it.
Also Stuck in time is incredible, If you know a shure fire watch stop, this effect will work everytime.