yeah, and I bet you just wear the pointy ears to hear the show better
As for Enterprise, they have already had alien time travellers and 1 human time traveller.
There is a temporal Cold War going on with some aliens from the future. One crewman of the Enterprise (the captain's Steward) was from the future, and was protecting the captain from other future aliens. I think that time travellor finally bought it, as well as the enemy time travellers.
Unlike a real Trekker, I couldn't tell you what episodes, but a little digging on the internet would probably bring them up. I'm just going off of memory from a show I never seem to miss. :)