I used the code from brainwallet to make a system that allows you to create a bitcoin address, encode the address in your gravatar image, and then send secret messages / get the bitcoin address of anyone who's done this with their gravatar. It's nice because you only need their email or the hash of their email. http://kybernetikos.github.io/VisualSecrecy/
It can either generate a key pair from your password or use your password to encrypt an imported keypair. If you use the address generated from the password, it is stateless, just as the parent suggested.
Yeah. I mentioned carbonwallet, because it tracks the balance, while brainwallet only shows the address. I personally prefer the latter, but the former matches parent's description more closely.
No required plugins, no mess related to p2p network connection, and just as secure/safe from government as anything.
Darkwallet - meh. A case of overcomplicating a simple thing.