At the start of the Great Depression, Kellogg's and Post were neck and neck in cereal sales.  Post slashed their marketing budget, while Kellogg's maintained theirs.  When the Depression ended, Kellogg's had a market share dominance that they maintain to this day. (Source)

This is a perfect example of what NOT to do in tough economic times!  When all of this is over, the buying population will remember the companies that stayed in front of them the entire time...through the bad times, as well as the good ones.  Companies that slash marketing dollars and do not maintain their presence will fade away in the public's mind.

Cutting trade shows from your marketing budget is cutting you off from your buying population.  Yes, the QUANTITY of trade show attendees has generally decreased in 2009.  But what has not decreased is the QUALITY of the attendees.  Companies may not be sending as many representatives to a trade show, but they are sending the ones that count. 

Numerous studies have shown that trade shows offer one of the most cost-effective ways to reach a large number of prospects, all in one place, all at one time.  So to me, it makes even more sense to exhibit during a recession!