The Australian 50c coins are also a spastic shape but I love 'em. Excellently weighted for use as a projectile, and they also do cool designs from time to time. Here is the standard though.
The $1 and 20c coins also seem to get cool designs from time to time as well. One of my friends is collecting as many of a specific type of 20c coin as he can. I think he has like thirty? Not even that much value but it's been fun stalking around for them. I stole one from some guy once because clearly he didn't need it as much as my buddy.