It's just too darn hard to find fast and free proxies in this day and age.
I think it would be a cool feature to have some kind of system for checking for valid proxies,
either by attempting to use it to download a few times and getting errors each time put that proxy on a 'black list' or something
Or by building an additional feature into the main program that goes through the users list of proxies and checks each of them.
Also another nice feature could some kind of automated error reporting system.
For example:
The rapidshare plugin goes down, which would be determined by trying rapidshare links, and after each of them return an error other than file not found, it basically says that the plugin isn't working.
It asks the user if they want to send an error report or something, which would send some kind of message to one of the admins, or some kind of automated forum posting bot.
the message could contain some kind of error message dialog, and a test link.
just a thought.
And as always keep up the amazing work!