A few years ago I wrote a small program to help with cropping and composing digital photos - its a simple grid overlay that you can use to judge whether lining image elements up with the rule of thirds, or golden sections etc. might help improve the composition. I find its a useful tool, though its only a guide, and often breaking the 'rules' produces better outcomes.
It's possible others here might find it useful too, so I thought I'd make it available. Its called Digital-Photo Crop Overlay (D-CPO) and you can grab it at http://www.steverox.info/DPCO/index.htm
. There are some instructions on the page as well, though it is pretty easy to use.
Sorry apple-heads, its a Windows only program