I use BreezyPrint (
http://www.breezyprint.com). Handles hundreds of different file types, it's easy to use, and cheaper than some other options.
Disclosure: I started the company, so I might be biased. <g> Then again, I was on the user side before this (as a helpdesk guy for a few years, then as a lawyer and law firm tech committee member), and there was nothing in the market that did the job well, so I left the law firm last September and created one.
Anyway, I don't want to spam the forum here or anything but BreezyPrint really is a pretty quality solution, according to the 80% or so of our free trial users who go on to convert to paying customers. We're rolling out a new version of the BlackBerry client next week, which will have some usability improvements as well as a new "enterprise" print category (more details will be available on the website next week), plus a bunch more cool features to come in the months ahead.
I'm always happy to talk to potential customers with questions, and the toll free number on the website rings my cell phone, so give me a call sometime if you want to discuss.
Good luck in your search.
-jared