I'm thinking here specifically of instruments that take a Bitcoin-like approach to trusted parties, eliminating them wherever possible and typically built with Bitcoin as their platform. (As opposed to simply having a real-world trusted entity issue a Bitcoin-containing or Bitcoin-related financial instrument in the traditional method).
Financial instruments include things like bonds, stocks, contracts, additional currencies, etc.
For example, I know jgarzik was working on smartcoin for a while (has development stopped?) and there are things like this you can do with coloured coins. Can anyone offer some insight on what is actually being developed re: these and other approaches, and especially what has reached an implemented, usable level?