First, let me say I absolutely love PitBull. I found the sheer amount of customization the unit frames has to offer a little overwhelming at first, but once I got a basic grasp of the interface, I've not been able to stop tweaking everything I see.
Anyway, for my frames, I've used Cabal's basic premise as a base, with the bars on top and bottom, and the portrait in the middle. I've simply added some things like the full bar, which I've set to display hostility, and done a bunch of tweaking to the various shapes, sizes, and object locations here and there. I've also utilized desprez's health bar visual scripts for my target frame.
Here's my druid's player frame when he's out of combat:
Here he is again when he's in combat with aggro:
Here's what my target's target and target's target's target look like (with a little dash of SCT):
Here's a random boss mob I ran past in Tanaris:
And finally, here's a random gnome warlock from the same zone:
In any case, everything's a work in progress, but that's what it looks like at the moment.
Once again, a great addon. Kudos to the author!