sop State-Oriented-Programming: reifying boolean state within an application using the metaphore of dynamic digital logic circuits, and hooking callbacks to edges: https://github.com/cyanogilvie/sop
rl_http A never-blocking (not even during connection phase) HTTP client designed for mission critical integrations with JSON REST services at scale (multithreaded keepalives, reliable timeouts, proper handling of encodings and HTTPS support): https://github.com/RubyLane/rl_http
Pixel (package) A package for doing reasonably fast raster graphics from Tcl. Includes many sub packages for loading / saving various image formats, and for display to various targets: https://github.com/cyanogilvie/pixel