I've checked out freesound before... its a little ....off putting. They make everything have a cc 2 license which means any sound used must be given credit, even if its one the hundred or so lousy fart noises.
Oops, I'm sorry, but I wrongly wrote the site url - it's http://www.freesound.org instead .com
And there are all sounds are licensed under the Creative Commons Sampling Plus 1.0 License
Look at this page http://www.freesound.org/whatIsFreesound.php and you could sure that all audio content there released under the CC Sampling Plus License.
But their site (not sounds) is under the CC 2 license that you've mentioned above
tulamide Thanks for sharing! It's very useful links!
By the way I've found a new site with absolutely free sounds http://www.freesfx.co.uk/
All content there are under CC license and may be used for any projects.
Their license agreement http://www.freesfx.co.uk/info/eula/