I have written a universal address and private key converter.
http://canada.host-ed.me/anycoinThe software is a portable but not yet ported Linux 32 bit software. That is to say, there is nothing really Linux specific about the source code. If Windows users really want it, they can donate using the donate box I have at the URL above.
The skinny is you can take an address from one alt-coin or bitcoin that you have control of (in other words its private key) and convert it to an address of some other alt-coin. For example, if there is a give away of peer coins (PPC), you don't need to download the PPC client to receive these coins as long as you have a bitcoin client or some other bitcoin-qt based altcoin client. You can export the private key from the client you do have and then reencode this private key for import into a peer coin client. Later, you can download the PPC client and spend the funds by following the instructions at the site above.