Erich Friedman's web site provides you with a myriad of resources to enrich your classes...and perhaps add some fresh challenges. Some of the web site's contents are being reviewed on the Resource Page and some on the Humor Page.
First, Erich provides a clever "Periodic Table of Mathematicians." Click on the "element's" symbol, and up springs a description of the "symbolized" mathematician. For example, "Ni" is Nicomachus of Gerasa, "Rb" is Julia Bowman Robinson, and "Ce" is Pafnuty Lvovich Chebyshev. Make it into a guessing game...give students the symbol and see if they can figure out the associated mathematician. Very clever approach!
Or, if you looking for interesting numerical trivia, a good source is Erich's "What's Special About This Number?". For example, 16 is the only number of the form xy = yx with x and y different integers.....or 62 is the smallest number that can be written as the sum of of 3 distinct squares in 2 ways. He requests help (and needs it) on some of them....e.g. 57, 86, or 93.
Other resources to browse through are Erich's humorous
"Mathematical Horoscopes," or his exploration of a type of number named after himself (e.g. "Friedman Numbers") which shows there is hope for all of us to have our own eponymic fame.