My understanding is that there are going to be lots of rivers in Skyrim - so do you like the idea of boats/ships traveling up and down the rivers with you having the ability to jump on? I picture sitting on a boat floating down a river and going between towns (while I enjoy the scenery). Same for caravans going through (potentially) dangerous territory (otherwise you could just run/ride to your destination alone). I'm thinking along the lines of World of Warcraft's ships between continents (I think the game is garbage...but having ships travel between ports in real time was one of the things I thought added a bit of immersion).
Basically, I love the idea of these going to hard-to-reach areas to make them useful (either due to danger of journey or geographic isolation).
And who knows - if they incorporate fishing perhaps you could fish off the side while floating down a river/crossing a lake...
What do you guys think?