Hammer is a parsing library written in C which aims to solve the language-theoretic security problem. It provides a parser which was designed from the ground up to be more secure as well as a selection of parsing back ends for the domain specific languages implemented thereby. It's also bit oriented, so you can use it to parse things which are ordinarily considered too fiddly (such as raw IP packets).
Bindings for other languages are available.
A wiki page that documents explanations for and origins of various types of radio broadcasts people picked up with software defined radios and analyzed with software like GQRX.
A framework for building cryptographic protocols so you don't have to do it from the ground up. Mutual and optional authentication. Multiple languages supported.
The indieweb is a movement in which people own their data, and run their own applications rather than other people's walled gardens. content is there and isn't censored arbitrarily. federation with some or all services is done with interoperable-by-design protocols and data formats. User interaction (replies, likes, stuff like that) are also federated back to your site(s).
The github repo of work pertaining to IoT communications and protocols over XMPP instead of other methods or networks. One advantage is that, by using p2p XMPP, devices could communicate with each other.