HDMI DDC (I2C) inspection tool
Latest version:
https://github.com/ApertureLabsLtd/hdmi-sniff
This tool is designed to demonstrate just how easy it is to recover HDCP crypto keys from HDMI devices, but it could be extended to decode all data passed over the I2C interface, such as MCCS, EDID, etc. You'll need an HDMI breakout cable (how to make one is described in the blog entry below), and a Bus Pirate:
http://dangerousprototypes.com/docs/Bus_Pirate
You'll also need a copy of Rich Wareham's hdcp-genkey to convert the sniffed KSV to a key:
https://github.com/rjw57/hdcp-genkey
For a walked through example, read this:
http://adamsblog.aperturelabs.com/2013/02/hdcp-is-dead-long-live-hdcp-peek-into.html
Enjoy! Adam