The 3rd annual Netsquared Conference just announced the winners of its mash-up competition — whose entrants are non-profit organizations using web tools for social good.

First prize ($25,000)

Ushahidi.com, a tool for mapping reports of violence and other unrest on GoogleMaps

Second prize: ($15,000)

Knowmore.org’s Firefox Extension, which alerts users when they visit web sites of companies with corporate abuse records, took the $15,000 second prize.

Third prize: ($10,000)

SocialActions.com, a search tool for social action campaigns, took home the $10,000 3rd-place prize. (They also found out they snagged another $10,000 cash injection from the Case foundation.)

(Here’s the list of 21 finalists .)

Here’s the video of the announcement and reaction shots from the winners: