Ran across an interesting article concerning the possibilities of Faster Than Light Travel (FTL). Seeing as how it looks to be that the only way to cover the vast distances between planets, star systems and galaxies is to travel far faster than light itself is to 'warp' space and time. In the article they mention two intriguing and surprisingly 'doable' approaches to warping space-time. If nothing else, these could be some good ideas for how your FTL drives in your stories function beyond the old 'Dilithium Crystal' chestnut.

Warp Drive Not Impossible Article