For those corporations whose executives and PACs view campaign contributions as just the tip of the iceberg, there's always shelling out for a party convention, as this USA Today article notes looking ahead to the 2008 nominating conventions in Denver and Minneapolis-St. Paul. Corporations says it's just a matter of "civic pride" but it looks suspiciously like access-buying to many.
Conventions are a big expense, and a huge opportunity for big corporations (like the Coors Brewing Company) to write a check and enjoy a few warm handshakes from party officials and candidates:
Corporate donations are legal for conventions, but Fred Wertheimer, a critic of the practice and president of the non-partisan watchdog group Democracy 21, said the donations give companies "the opportunity to buy access and influence." In contrast, candidates are limited to raising campaign funds in chunks of $2,300 or less and cannot accept corporate or union cash.
Again, not likely a situation of outright bribery but another example of access that the average American voter can't buy.