Mynyddcymro - why don't you do indoor driving trials with him it is SO much fun and there are special classes for small pones. See www.indoordriving.co.uk for more info - the forum is very helpful. They pretty well cover most areas in the UK and it is something to do in the winter.
Patchworkpony - I'd love to do something like that but have no way of getting the cart there, plus I don't think (I really know nothing) it would be suitable, my grandad built it for my 18th and I'd be mortified if I damaged it!
It would be wonderful to get into something like that but currently just getting the pony out and about to shows usually leaves me begging for transport!
Mynyddcymro - I know what you mean about transport. You can just get a Shetland and a driving carriage into an Ifor Williams 510 trailer if you travel the pony up the front with a partition between them. Just keep doing the lottery!
There is no limit to what these little guys can do. I have quite a few of them - but one particularly special little chap - Rascal. He has done so much, he is only 8 this year, and I am currently working on breaking him to drive. My biggest problem with him is working out what exciting thing he can do next!