Here is a link to FPGA-based machines. Pick at least one and as many as four machines that you think are noteworthy (unique, clever, or distinguish themselves in some way). Find out about more about each one you pick by following the appropriate link or through a web-search. You do not need to write anything up, but be prepared to discuss your choices in class.
Alternatively, if you know of other machines not on the list, you could choose those.