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: 
You can test Facebook applications locally if you add an entry to your hosts file which points to any subdomain of the root domain you gave Facebook. For example, if your domain is example.com, you can add entry to your hosts file pointing fbtest.example.com to localhost (127.0.0.1).

You can then test away locally without having to edit your Facebook app configuration (assuming your local server is set to serve the same content to all subdomains).

Alternatively, if it's important to have the exact domain, you can just add an entry for the root domain. It just means you won't be able to access the live site while testing.
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.