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Fun and value can be found in aggregation. Using the Feed API, Emfield, and Feed element mapper, it becomes easy to create awesome video aggregators that pull in topic specific videos from multiple video sharing services. The Wall-o-Cello Videos shows hundreds of videos from YouTube.com, Blip.tv, MetaCafe.com and Google Videos.

Yahoo! Pipes (screenshot) is an ideal tool for creating custom aggregation filters. CelloRoller.com uses Y! Pipes to track specific cellists, pulling information from across the entire internet.