Here's how you can control the information about you that friends bring to apps, by changing the categories you allow them to use.
1. Click the arrow in the upper right corner of the Facebook interface.
2. Click on Privacy Settings.
3. Click on Edit Settings in the "How people bring your info into apps they use" section.
4. A menu will appear with categories of information. Click the ones you want your friends to be able to bring to their apps, uncheck the ones you don't.
5. Click the Save Changes button.
Here's a list of the categories:
Family and Relationships
Religious and political views
If I'm online
My status updates
Education and work
Activities, interests, things I like
My app activity