Just wanted to share with you all a great web site that offers cool free and high quality icons for all your apps:

http://www.iconspedia.com
For example, expand the categories in the left hand side and search for what you need, here are some flags for example:
http://www.iconspedia.com/cat/world-flags/

In addition to the above, here is another site with a big archive of free and high quality icons.

If you just starting to develop and are not sure what to do with such icons in your app, here is a video tutorial that shows how to use them:
http://www.youtube.com/user/gumuz#p/u/7/LYF0spYkXUs

Enjoy!