Got some breadboardable electronics and a couple extra coffee
cans lying around? Why not use them to build your very own
Doppler radar?  MIT's OPENCOURSEWARE, the school's open
education initiative, offers a free online course and resource
materials that will guide you through the entire process, while
educating you on the finer points of radar engineering. Your
Folgers-hack won't be powerful enough to track precipitation,
but it'll do just fine as a DIY speedometer, as the video up top
demonstrates.  Visit MIT for more info on what you'll need to
get started, and other ideas on how to make use of your radar
system. [Via MAKE]