The sigrok project aims at creating a portable, cross-platform, Free/Libre/Open-Source signal analysis software suite that supports various device types (such as logic analyzers, oscilloscopes, multimeters, and more).
sigrok-dumps is a collection of logic analyzer example data, covering various protocols (e.g. I2C, SPI, UART, etc).
sigrok-dumps is in a usable state and has had official tarball releases.
See http://sigrok.org/wiki/Example_dumps for details.
Unless noted otherwise, all dump files are hereby released into the public domain by their authors.
https://lists.sourceforge.net/lists/listinfo/sigrok-devel
You can find the sigrok developers in the #sigrok IRC channel on Freenode.