Have a small budget but need to make a big splash? If you are hosting clients at a large scale event and providing transportation, consider branding the limos and shuttles to shout your brand to the crowds, and make your clients feel special. You're already paying for the shuttles to drive all day (past thousands of people) so why not put them to work.
The stickers shown in this photo are easy to attach and leave no damage on the vehicles. If you need a resource, two companies to consider for this type of branding are BLR Signs or Giant Impressions (see Hot Vendors). In the case of Yahoo! at the ATT Pebble Beach Golf Tournament fans yodeled as the limos went by - too fun!