https://github.com/Stunning/gimp-export-layers-to-css
Currently I'm using Gimp 2.6 on Ubuntu cause after a Windows update now I can't boot into windows because all I get is that ever so popular blue screen of death. I'm debating on installing Windows 8.1 beta again and leaving Windows 7, but don't care as I hardly use windows anyway.
I'm running Ubuntu 10.04, I found various articles on installing Gimp 2.8, but none seem to be working properly as the PPA is no longer active.
Never the less I found
this plugin on Github which is made to export layers to CSS. I haven't given it a try yet, but I thought I'd share as this may come in handy.
There's also
this one to export layers as sprites.
There seems to be some issues with Gimp on Win8.
Getting Gimp 2.8 on Ubuntu 10.04 is very complicated because there is a dependency avalanche. IIRC to run Gimp 2.8 without too much trouble you need at least an Ubuntu 11. 10.04 is out of service anyway.