With CX's permission, I extended on his synchronous up counter to make it an up/down counter :D

It currently counts up from 0 and down from 100000000000000 (thats binary btw). You can change it if you want, you just need to change where the wire directs to.

Basically its just the counter hooked up to a 15 bit ALU that can add/subtract. When you change the input from up/down, it subtracts the counters output from the one on the thing. Nifty eh? Plus its only 4 or so blocks wider than the original as I used my tileable FA as the adder.