Jesse Rutherford (@BentTronics) gave us an in-depth look at the 555 timer IC (wiki).

Jesse runs Bent-tronics.com and wrote The Ultimate Beginner's Guide to the 555 Timer (Amazon).

Some great 555 projects:

• 555 Decimal Adding Machine

• 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.

The giveaway is Jesse's book and the components to build the projects in his book.