Not your daddies mass driver

http://en.wikipedia.org/wiki/Tether_propulsion#Tether_cable_catapult_system

It's an idea by the late Dr. Forward- a mass driver where the mass
driver coils pull themselves down the length of a conductive cable
that powers it, and then before they reach the end the coils slow and
stop themselves and the payload carries on.

Payload could be quite heavy, and g's are low, so payload could be human.

Top speed > 30 km/s (enough to get to Mars or Jupiter- if you can work
out how to stop!)

--
-Ian Woollard

"I think we all would have been a lot happier if they hadn't landed a
man on the moon. Then we'd go: 'They can't make a prescription bottle
top that's easy to open? I'm not surprised they couldn't land a man on
the moon. Things make perfect sense to me now.' "