http://www.cypherpunks.ca/otr/donate.phpOTR is one of the best pieces of encryption technology available today.
It does all the right stuff from a security perspective but more importantly it does things in a way which is deeply thoughtful about the user factors. While it's fairly difficult to use GPG/PGP and thus really hard to get people to use them: OTR works pretty transparently and in doing so turns otherwise treacherous commercial chat networks into ones that are a little less able to betray their users.
OTR opportunistically encrypts whenever it can (
my minor contribution to the protocol, years ago), and allows strong authentication when the users are willing and able. For authentication you can do the boring fingerprint comparison stuff, or it can use a challenge question based on a zero-knowledge-proof: The math is complicated but the result is security that works for how regular people usually talk, no dorky key signing parties required. It certainly doesn't depend on any of the horrible hole ridden and difficult to use PKI CA infrastructure. If you're not up for authentication you still get crypto which kills passive snoops dead.
Unlike most prior chat encryption systems when authenticated it operates without actually cryptographically signing your messages and creating proof of what you said that a treacherous counter-party could show to others against your wishes. Non-repudiation is very good, but you should only have it when you want it and know that it's there. OTR tries to minimize surprises.
In spite of all the great things that OTR already does there is still a lot left that could be done: Support for additional chat systems and clients, further attack hardned software, additional authentication options,
multiparty chat, encrypted file / multimedia transmission, formally specifying the protocol in an internet draft, and many other things. While there are many commercial companies out there creating snake-oil closed source crypto— stuff that inevitability turns out insecure— are now exploiting the NSA/prism stuff to make a pretty penny on the various app stores, OTR has continued trucking along delivering the real deal to everyone at no cost while advancing the art in both cryptography and cryptographic usability.
I think in general the Bitcoin community can learn a lot from how OTR uses technology to serve human interests without compromising on the security— something we should always strive for in the tools and infrastructure we build. Without secure communications our whole economy is more fragile: Bitcoin depends on information being easy to spread and hard to stifle.
I've donated: OTR is something that many of us have reason to
support.