Probably suggested before, but tried thoroughly to look and couldn't find it so apologies if so.
Let us link sleds together, maybe only a new type of sled can be linked and maybe only linked to the same type of sled. Whatever costs have to be implemented in order to make sleds linkable would be super, super welcome. It would be super fun to haul around the wilderness with a sled train decimating deer and collecting granite boulders and such.
I'm thinking that you would start pulling a sled, sled A, then go to a second sled, sled B, right click, and select "Link" or "Chain", and you would then be pulling sled B and sled B would be pulling sled A.
To unlink, just go to any sled that is being pulled by another sled and right click, select "Unlink" or "Unchain", operating much the same as "Stop".
Maybe there would be a limit to the length of the chain but honestly it would be hilarious to see a chain of like 50 going by xD If there was a limit then I'd suggest maybe 6-12 being the max, more the merrier though.
Presumably this chainable type of sled would be valuable and cost about double as much as a cart but only hold 4 items since the extra sturdiness of being able to drag a long chain of carts behind it is introduced. It should be the same speed as a cart and should also be normal speed on paving (I guess only if all sleds are on paving).
I'm thinking maybe 2 blistersteel, 4 oiled boards, 8 dry boards, 10 nails, 2 ropes... Something like that. (see http://salemwiki.info/index.php/Cart for comparison)
The high cost and usefulness of it would mean if someone ran across you while you were pulling a chain of a dozen through the wilderness they would have a high incentive to knock you out and take them... Or simply threaten to and try to coerce you into pissing off and letting them keep them. It would be pretty easy to interrupt the chain too. I think this would add a lot more interesting wilderness encounters.
I also would love to see this on the water, boat trains would be cool as hell and would make trading with (*cough* looting from) neighbors up the river a lot more fun. Cart trains on land would definitely be the most useful though. Thanks!