Please check out the link below for an excellent lesson in simple accessory conversions. I have always used a pin-vise twist drill for exchanging hand accessories, but here is a hot-pen technique. The advantage of the hot-pin is that there is no loss of bulk plastic. It should expand outward and maintain total quantity.
The S*R figures are all full-bodied, so lend well to the hand-drill technique, but especially for other makers with tiny little fingers, the hot-pin should be better. Please see some neat conversions for this very fine and popular set:
I make the point about conversions in the "cost" reply to Andrew above.
If you look at the standing figures minus banners they make great horse handlers or handing a lance to a rider together with the standing figure who looks as if he is about to mount the horse or another handler. The figures can be used to represent several periods. The wenching ones could be "vikingised" for instance. Don't forget the heralds could also have the plastic pennants removed.
For the really mad, a troupe of jesters could be made from multiple sets with a bit of judicious bending.
I'm looking forward to putting some swords, axes, spears and even knives in both the horse figurine's and foot figurine's hands just to build up some numbers. The horse guys would make an impressive looking column leaving or entering a castle with a wagon.
You also make a very good point. This nice soft plastic still has "memory" as you suggested for the jesters. Small changes do not require hot water.