My band has a baritone guitarist.
He tunes it A to A (A D G C E A), the A D and G are the same pitch as the same strings on a bass.
We use it to fill the sound out between the bass and the guitars when we go LOUD. He also does more detailed work on the upper three strings from time to time. It sounds a bit wank playing open chords, even clean, but distorted 5ths sound filthy and ace.
I'd post some mp3's but he's only played on our latest recordings and we're still waiting for the mastered Cd back. So you're spared.