According to relativity, we can easily travel into the future by traveling noticeably faster than everyone else. The 'distance' into the future would depend on the speed you travel and for how long. It's even been confirmed experimentally.
http://en.wikipedia.org/wiki/Time_dilation
Don't know any way to get back though (unless wormholes exist).
This is my understanding as well. It is important to distinguish between time traveling to the past versus time traveling to the future.
Traveling to the past, as I have heard it explained, requires traveling faster than the speed of light. The wormhole possibility is something people talk about to move faster than light -- essentially, the wormhole provides a short cut between two points in space and, therefore, going between the two points is possible to do more quickly than light. This type of time travel just allows someone to see the past -- like watching TV, you cannot actually physically interact with that past. We are actually looking into the past when we look at the stars. Since stars are typically many light years away from us, we are seeing light from the stars that left years ago. A star may have exploded right now and we would not visually see that on Earth until a few years later.
As for traveling to the future, one theory relies on the concept that time moves slower for a person if he is moving faster. There have been experiments where an atomic clock (i.e., a very accurate clock) on a fast moving vehicle (e.g., plane, space vehicle) shows less time having elapsed versus an atomic clock on the ground. So, the thought is that, by moving very quickly for a long time, a person may have aged by one year while the rest of the world has moved ahead by multiples of that time.
