If you have the Print dialog already open in some Apple applications (e.g. Safari, Mail, TextEdit), pressing Command-P will open Print and Fax preferences in System Preferences.

It seems to work inconsistently among Apple's programs. For example, it works in Safari and Mail, but in iCal, you have to hit Continue and then cancel the print dialog for the System Preferences to appear. In Preview, it seems that doing Command-P when the print dialog is already open sends the current document to the printer. So this behavior is inconsistent among Apple apps, and doesn't work in the non-Apple apps I've tried (Word, etc.).