Wouldn't a railess railgun be just a gun?
A coilgun works in a similar fashion without the projectile touching the sides and I suppose you could look into mass drivers too.
From Wiki: "Mass drivers can be used to propel spacecraft in three different ways: A large, ground-based mass driver could be used to launch spacecraft away from Earth, the Moon, or another body" which sounds like it could fit your sattelite launching criteria.
http://en.wikipedia.org/wiki/Coilgun
http://en.wikipedia.org/wiki/Mass_driver