John Cletheroe's USA and Canada Holiday Hints
Basic travel trade jargon.
http://johncletheroe.org/usa_can/jargon/index.htm

Positive Space
Online resource directory and Q&A service for travel agents.
http://www.positivespace.com/

The Practical Nomad
A detailed article about PNRs, the industry jargon for a booking or reservation.
http://hasbrouck.org/articles/PNR.html

Travel Industry Dictionary
Dictionary of terms, phrases, slang, nicknames, abbreviations and acronyms used by the travel industry.
http://www.hometravelagency.com/dictionary/