Not sure if you've read about time dilation:
http://www.phys.unsw.edu.au/einstein...e_dilation.htm
It's not exactly 'traveling' through time but you age slower. Therefore, if you would travel at an incredibly fast speed for an extended period, you'd age slower allowing you to live longer.
As for truly traveling through time (ie; back in time), I've always thought of it to be unlikely.. Think about it if time travel is possible, why haven't we had any visitors from the future?
ref vid about time dilation:
http://www.youtube.com/watch?v=KHjpBjgIMVk