Question: I would like to avoid class loader leaks due to un-removed listeners. To facilitate this i believe weak or soft references to listeners would help. Strictly the only Collection methods i need are add() and iterator().

Are there any foss libraries with a Set or List that uses Weak or Soft References. 

Any suggestions would be appreciated, otherwise i will write my own.

Answer: 
Enter `http://localhost/Users/home/Documents/facebook/` as your "Site Domain" on the developer app:

<https://developers.facebook.com/apps/>{api\_key}/summary

Replace {api\_key} with yours; or find a link at <https://developers.facebook.com>

Interestingly enough, Facebook lets you type anything into the domain so it can be an offline URL (such as localhost or a local port) and Facebook will redirect to it after authentication.
Check the 'Desktop Apps' section of <https://developers.facebook.com/docs/authentication/>
This explains how to do authentication where there's no server involved, it's aimed at desktop apps but a browser toolbar should work in a similar way