As a nightblade, my optimal pvp situation is killing someone from stealth who is passing by on a horse. They are pretty defenseless and the health loss usually puts the following fight to a close quickly.
This got me thinking. Why are we defenseless on our horses? We should be able to use the bow/bow skills from horseback. This would create a fast paced layer of combat missing from Cyrodil. It would also increase the viability of a skill morph which is rarely used, the anti cavalry caltrops. Horse back battle will take an additional layer of skill, positioning, and make all the travel we do in cyrodil not feel like it's separate from the action but a huge part of it.
I wouldn't be opposed to adding a 3rd skill bar when mounted to include skills that can be used when mounted ie rapid maneuvers and maybe a mounted execute for when riding by a weak enemy.
Love it? Hate it? I'll go back to ganking now.