check out these pages on Stardrives ..
by The Challenge To Create The Space Drive , Marc G. Millis, NASA Glenn Research Center
and
Prospects for Breakthrough Propulsion from Physics, May-2004, Marc G. Millis
These give straighforward but good indepth summaries of the various options, and of current research projects - written for an engineer, really.
And here's a pdf article on hyperfast travel in general relativity .. I chose it because it's very readable, you can skip the mathematics. I can't vouch for his arguments though as I'm not that advanced ..