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.
In order to develop and publish a Facebook application, you must provide a web accessible URL that Facebook can query. If you have webspace you can upload to or make your IP available to the web for Facebook to call, it should solve your problems.

Facebook will allow you to put just about any valid url into the box, however when you go to use it for logins or general use, you will begin to notice errors, since Facebook's spider cannot fetch the url.