Ok, I just got these two amazing pieces of work from SimpleShot. Call me a little biased, but I NEVER knew slingshots shooting could be like this. These things launch a 3/8 in steel ball at jaw-dropping speed (and with a little work, accuracy). I see, now, why slingshots have the following they do.
You can see these slingshots and a lot of others (way cooler than these ones, actually) at simple-shot.com.