Yahoo Pipes

http://pipes.yahoo.com

A powerful composition tool to aggregate, manipulate, and mashup content from around the web.

One of the  most usefulness of this tool was realized when I could aggregate all the photo together taken by different friends in different cameras and uploaded separately in their Picasa or flicker web albums

I just took the RSS feed of different sources and used a simple UNION operator using yahoo pipes and Bingo ! All the pictures of the event are now together and can be distributed as a single stream.
http://www.jumpcut.com/media/flash/jump.swf?id=F4396574585311DC87A2000423CF0184&asset_type=clip&asset_id=F4396574585311DC87A2000423CF0184&asset_url=/media/dyn/84/2fc0/7aaa8b5c719b614fb3f846fd17/lq.flv&eb=1