You can open an account on an exchange like btc-e and then fund it with your coins.
I have an account at btc-e but how do I fund it with a paper wallet? All I have is a piece of paper with the address and private key on them.
The easiest way I know is to import the keys into the desktop client wallets. Downloading Namecoin-Qt [for Linux] is a bit of a pain in the backside though.