Somewhat late on noticing this, but the Twitter Vote Report was a mashup project that aimed at pinpointing (& helping to solve) problems people in the US were having in voting in the Presidential elections "As news outlets and blogs will report on Election Day stories, we are building an invaluable resource for thousands of voters to get immediate help. From questions like "where do I vote" or "how do I make sure that my rights are being upheld," Twitter Voter Report augments these efforts by providing a new way for voters to send text messages (aka tweets) via cellphones or computers which will be aggregated and mapped so that everyone can see the Nation's voting problems in real-time." (source)
The main input was people using Twitter. The result of there efforts was an embeddable dynamic map that showed where problems were, and enabled you to see the actual tweets if desired: here it is still on the blog http://blog.twittervotereport.com/ According to the Center for Social Media there were 12,545 submissions from over 7,500 accounts.
This demonstrates people discovering useful ways of using ability of twitter to gather input from dispersed sources and channel them using indexing (hash) tags, particularly combined with other data such as geographic location. There are issues concerning data reliability, since people had to use a hashtag of their zip code as well as the hashtag for the exercise (so there could be misleading information if they got either of them wrong) - but also impressive in teaching so many people the power of indexing / organising information ;-)
Photo by Sheila Webber: Bowl of cherries, July 2009