Some great 555 projects:
555 found in a drill trigger speed controller as seen on the Ben Heck Show
555 found inside a solar charger controller, video by Julian Ilett
Somehow, despite it being in the plan, we didn’t mention the Evil Mad Scientist The Three Fives Kit: A Discrete 555 Timer which builds a 555 Timer out of discrete parts. If only the creator would come on to talk about it and his other cool projects. Note that EMS also has a great description of how the 555 timer works.