Cabe Atwell wanted an authentic arcade experience at home. So, he built a replica of the Street Fighter 2 control console and a metal dance mat and has now hooked up a Raspberry Pi using emulation software. The console and the dance mat are hooked up to the GPIO and he’s finally got the home gaming environment he always wanted. Many years in the making, you can read more on the Raspberry Pi Foundation blog and also at Element 14.
Instructables user darkstar1 has documented his project which uses a fogger/mister machine and a PowerSwitch Tail II to create a Pi-controlled aeroponics system to grow plants from cuttings. You can read how he did it here.