Timesifter, Gate to the Aether, Furnace of Wrath etc, are fun

(they are in our chaos stack, too). You totally have to put a Shared Fate in there. Also, some sort of hand revealing effect like Revelation can make things really interesting (or perhaps Zur's Weirding).
We have semi-board clearing effects in the form of Inferno and Soulscour (which I think are more interesting than something that just wipes out everything). We also play with the rule that chaos spells can't be countered (athough they can be responded to and permenents can be destroyed once they have entered play, although they are subsequently shuffled back into the stack).
We also do the thing with the 1/6 at the start of each palyer's turn after each player has had at least 1 turn (2nd time around). It doesn't really matter, but for 6 we flip the top card of the stack and for 1 we flip the bottom card.