OK this is cool. I saw these arrows all over the place when I was in San Jose. They marked the route of a walkathon that took place on Saturday while I was at the GAS conference. The starting line was right across so the street from the glassblowing in the park. You can get these arrows online from RouteArrows.com
Check it out. They are inexpensive, stick to concrete and asphalt, can be easily removed, and come on a roll. Super easy. RouteArrows has lots of other event signage and with a little imagination can be used for marking paths and providing direction for non-sporting events. Think about community-wide scavenger hunts, or a sequential event where guests travel around town. Plus they could really add some fun to a typical indoor conference venue!