Yardena Arar highlights the coolest startups, innovators and exhibitors on the Expo show floor:

The Web 2.0 Expo at San Francisco’s Moscone Center West, which wraps up today, doesn’t take up a huge amount of space: Startups predominate, and most don’t have money for big flashy booths. But there’s more cool new technology per square foot here than at many big trade shows.