Fodder for a Transit Authority article, perhaps, but I just came across a useful online tool that could help shave quite a bit off of your T&E's.

Currently in beta, Mobissimo is an airfare search engine that scours 60 airlines and carriers to help business travelers -- and others, natch -- find the least expensive fare possible.

Doing a quick check for roundtrip fares from New York to San Francisco, the results reflect a range of $2,000. Each result indicates where the tickets come from (services such as Orbitz or direct from the airline), what airline is offering the fare, and how to book a ticket. Very useful!