IceHUD has that nice numeric (or dot based) display right there in the middle of your screen. Incedentally, this same display works great for Lacerate stacks for bears and Maelstrom Weapon stacks for enhance shammies. My energy shows up as a separate HUD bar.

Lately, however, I’ve been moving that stuff out of IceHUD (leaving it just for tracking my health, and the mob’s health/mana). I’m using PowerAuras alongside the IceHUD display with a set of auras suggested by the enhancement shammy column at wow.com. There’s an aura that looks like a circle divided into five segments. As my combo points, lacerates or maelstrom weapon applications stack, the circle’s segments fill up. When it hit’s 5 stacks it starts spinning. The arrival of segments and the spinning of the completed circle are just enough of a change in my peripheral vision to allow me to track what’s going on (and that it’s time to unleash hell).