Cut&Slice me looks like an interesting free add-on to Photoshop CS6. According to the site:

• Create overlapping slices exporting only what you need in the minimal time with the maximum detail: no more cut gradients.
• Export easily your button states
• One Design to rule all resolutions: For iPhone design for Retina, for Android design for xhdpi and then export to ldpi, mdpi and hdpi with only one click.

I haven’t yet gotten to try it out, so feel free to post feedback.