Stephen Hawking thinks that these is one good way to travel through time.... just that it involves some pretty advanced space craft, a black hole, and people who are interested in only going forwards in time.
For this to work - a fast (I MEAN REALLLLLYYYY FAST) space craft would have to make rotations around a black hole while balancing the gravitational pull of the black hole with speed. The entire purpose of this it to be next to a high concentration of mass, thereby gaining the ability to slow down time in one's local location (the spaceship) in relation to the rest of the universe (I can't explain all the science, but space and time are related - the the higher the mass - the more distortion in time). I don't remember all the details, but it seems as though every year passed on the space ship would be two years on the outside.
Now its not true Sci-Fi time travel, but time travel is a rather vague term to use and this fits the description. Its not pratical.... it serves no real purpose..... and it only goes foward in time.... but... its time travel, and it may be the closest thing we can get to the "real" deal.