In celebration of European π Day 22/7/2014, I have just released the "proof of concept" version of Flavia: the Free Logic Array. Flavia was inspired by a great discussion started in 2012 Role for FPGA or CPLD with Raspberry Pi which included using Raspberry Pi as a platform for teaching programmable logic. The problem is that vendor tools usually only run on x86 PCs, and never on ARM, and there is no open-source FPGA tool chain that can run exclusively on a computer like RasPi.
That is, until now. Flavia is a "CPLD in an FPGA", which uses FPGA look-up tables (LUTs) to implement both logic and routing. Since Xilinx documents ways to find the locations of your LUTs and flip-flops in their otherwise undocumented bitstreams, it's possible to program those LUTs to make a reasonably nice CPLD that can be programmed using exclusively free-as-in-freedom tools.
If you're interested, take a look at Flavia: the Free Logic Array. Flavia is part of XXICC (21st Century Co-design) release 0.0k. I haven't been able to upload all of the 0.0k release files because of a temporary element14 problems -- I hope to be able to do that soon. However, there should be enough there to get you started.