Sleep is a form of Time Travel. Close your eyes one night, and bingo! It’s the next morning, your alarm hasn’t gone off, and you’re late for work… 
Seriously though, I’m rather fond of the Paratime idea (made famous by H. Beam Piper in the Paratime Police and Gunpowder God/Lord Kalvan Of Otherwhen stories, but used more recently by Michael Crichton in Timeline).
I’m more inclined to say that the closest thing we’re likely to get to actual time travel, however, is hyper-realistic computer simulations (kind of like the Holodeck from Star Trek), in which any possible scenario can be fed into the mainframe and a realistic simulation thereof can be produced.
Of course, If Time Travel in is truest sense were developed, I think it would lead to an interesting number of oppurtunities- ranging from Pan-Temporal Imperialism/Trading, to Dinosaur Hunting Safaris, to simple Time Tourism- not to mention definitively answering a few questions about some of the major religions, too…