28 January is International LEGO Day, commemorating the birth of the LEGO brick - Jay's Brick Blog
LEGO Ruler and Sorting Tool - Tom Alphin
What are LDUs and how do they relate to LEGO bricks? - Bricks
What is the interference lock offset of a LEGO stud/hole such that it fits snugly into another piece? (i.e. What are the snap mechanism dimensions?) - Quora