A neat little sling shot I picked up somewhere: the Slingo, made in Chicago, USA.
The neat thing about the Slingo is the magazine--that's right, a repeater (sort-of) sling shot!
The fold-down magazine allows immediate access to the bb shot; the tension of the rolled tin funnel 'lips' is perfect to maintain the position of the next shot for a fast grab, right down to the last bb.
The magazine is of sufficient size to hold about a tube's worth of shot, plenty enough for an afternoon's sling shot outing.
A simple but ingenious little sling-shot; I've recently seen this very same design used in a modern pellet magazine application.