Found this gem on CreativeBits:

InTips is a “tip of the day” plug-in that helps both novice and experienced InDesign users learn to use the program more efficiently.

InTip’s tips and tricks for Adobe InDesign were written by bestselling book author David Blatner as a way to help publicize the power of InDesign and its plug-in technology. Blatner notes, “I consider this ‘promoware.’ InDesign users get free tips, and we get to spread the word about other cool InDesign products. Everyone wins!” (Hat tip: ID: Tip-A-Day Giveaway!)