Steve Jackson Games makes this Tally Mark d6 Dice Set.
Jean Simonet has launched an already wildly successful Kickstarter for his Pixels dice–LED-lit dice that feature Bluetooth and wireless charging.
Pixels are the coolest dice you’ve ever seen! Full of LEDs, smarts and no larger than regular dice, they can be customized to light up when and how you desire. Incredibly strong, smooth and sharp, they work for several hours at a time, after which you can simply recharge them with the accompanying case. Pixels know which way they roll and can communicate with your phone or tablet via Bluetooth. This means they will work with Roll20, Foundry or any one of your favorite online platforms.
Non-transitive dice are beyond weird. As seen in the image below of Bradley Efron’s four-dice nontransitive set, these dice are not like normal six-sided dice in that each has a unique pattern of numbers.
Imagine setting up a game where each person picks a die and then rolls that die 50 times. Whichever die rolls higher, the most times wins.
The purple die will roll a higher number than the yellow die 2/3rds of the time.
The yellow die, in turn, will roll a higher number than the red die 2/3rds of the time.
Finally, the red die will roll a higher number than the green die 2/3rds of the time.
Here’s where the weirdness of the non-transitive nature of the dice comes into play. The green die will roll a higher number than the purple die 2/3rds of the time.
Wikipedia has a nice entry on non-transitive dice, including a detailed look at the probabilities of the Efron dice. The set of Efron’s dice in the image is available for $5 plus shipping from the National Museum of Mathematics.