The default bar symbols should be customizable.

The lightning bolt and heart are obvious, but the ECG? No idea what to do with that. I think that these graphics should be freely editable to suit the needs of the DM.

Considering the ECG is tied to the red bar, I suspect it's actually for health... what, then, the Heart is for, I have no idea. Related suggestion: customizing the colors of the bars.

I use heart and ekg for stun and physical damage (respectively) in my SR4 game, however I agree that customizing the symbols and/or colors would be nice!

For Pathfinder, I'm using the ECG slot for AC, the green heart as HP (obviously) and some players are using the lightning bolt for abilities that they can do a certain number of times per day. Even if we can't add our own images from the art librray, what if it's just a set of basic icons you can choose from a list perhaps, like in the old days of IM avatars? You click on the picture, opens a new window filled with little icons (like a shield, some stars, a clockface) and you click one to choose it for that bar.

Heart is Health ECG is Healing Surges Lightning Bolt is Temporary HP at least in my 4e game :) I'll add changing colors & icons to the list however.

In SW Saga Edition I've been using: Heart as Health ECG as CT penalties Lightning bolt to display Reflex for quick reference.

I have to say that my first thought when using it was as per Paul's suggestion as I was using Skype at the time I was playing :)