There are many other finishes out there.
http:// www.lauerweaponry.com
Offers DuraCoat which is basically a painted on finish.
Kimber, springfield and few others offer a duracoat like finish on their handguns.
There are many others out there and I am not going to debate which is better, they are all basically the same and prevent rust by providing a barrier between the weather and the steel.
Blueing is more of a cosmetic finish than a form of protection, it is a form of rust in itself and really offers no corrosion protection, but looks nice.
The military parkerizes most of their weapons, this leaves a semi rough surface that sucks up and holds oil to protect the metal (this is also a good "primer" for the Duracoat type finishes).
Do a Google search on gun finishes or you can pickup a fairly cheap book on metal finishing or browse through Midway or Brownells web sites for metal finish options to get a taste of what is out there for free.
Are you looking for anything in particular? Blueing is fairly cheap to do in batches and is the typical finish most people have come to expect, I suspect that is why it is so comon.