I think it might be interesting to people to know about a nifty shield I found a while ago that includes a Altera Max II CPLD. The UnoProLogic shield by Earth People Technology is designed for Arudino but I have connected it to Galileo without problems. Just some wire jumpers are needed to power it off of the Galileo 5v supply. I purchased it just to experiment with VHDL, but I think it could be handy for other Galileo users as an option to help deal with the limited IO speed. CPLDs are programmable logic devices (similar uses to FPGAs). This makes it possible to place some pretty complex digital logic on a single programmable chip. Rather than having all your IO logic written as a Galileo program on a CPU, put some of it on a CPLD. So maybe instead of doing a bunch of slow pin flipping, just flip a single pin to trigger the CPLD and have it do the timing sensitive work while waiting for the results.
What I like about this board is it is cheap, $20 on Amazon http://www.amazon.com/Earth-People-Technology-UnoProLogic/dp/B00EYXM56G (the one user review is my own ) and has a FTDI-based JTAG programmer that is removable included. The designer targeted it for high-speed data capture over USB and there are some samples on how to do this. One really intriguing possibility is to plug in the USB port off the shield into the Galileo USB host port. This would open up even more IO options. I haven't tried the USB this way, I have way too many other projects going on, but I see a lot of potential here.
I don't know how the company can keep on making the board as the FTDI module alone goes for $27 on Mouser. There are other cheap CPLD boards but the lowest price I could find is on SeeedStudio for $15 but it isn't comparable because it doesn't come with a JTAG programmer.There are plenty other more powerful boards, but as prices go, I haven't found anything better than this.