This workaround may be specific to a combination of Macbook Air 6,2 running Ubuntu 14.04 (Trusty).
I've been recently experimenting a lot with Linux Containers, and needed to have access to a native Linux environment. One of the easiest ways I found to achieve this was to boot from a USB 3.0 stick - as this both doesn't take away precious internal storage, and avoiding rEFIt/rEFInd altogether.
There were numerous problems, but one of the more annoying ones was that the backtick and tilde keys were not working as expected. In my case, I was getting < and > instead of backtick and tilde. More on the installing and fixing to be covered in a separate post.
Luckily, there was a workaround:
echo 0 > /sys/module/hid_apple/parameters/iso_layout
(You will need to add this to somewhere like /etc/rc.local to make it permanent.)