Except all the apps you can download from F-droid, here is some additional ones:

1. 安能饭否

https://github.com/fanfoudroid/fanfoudroid

http://code.google.com/p/fanfoudroid/

2. foursquared (Abandoned)

https://code.google.com/p/foursquared/

3. Beam (Android XMPP)

http://beem-project.com/

4. Replica Island (Game)

Development Blog: http://replicaisland.blogspot.com/

http://code.google.com/p/replicaisland/

Talk link about Android Game developement: http://www.youtube.com/watch?v=U4Bk5rmIpic

5. Flickr

https://code.google.com/p/flickr-viewer-for-honeycomb/

6. wordpress

http://android.wordpress.org/

7. Apps developed by Square Open Source

http://square.github.com/

https://github.com/square

8. Apps developed by Open intents

https://code.google.com/p/openintents/

http://www.openintents.org/en/