Five Ten have come up with a nifty looking product - a kit which you can use to mix and apply rubber to your climbing shoes. The rubber comes in a ground particle form which turns into a paste when mixed with a solvent. You can then apply the paste to your shoe where ever you think it needs it - the obvious place is the toe end above the rand, for toe hooking or jamming.
Image from rockclimbing.com
Here's the video from Five Ten describing the process
And here's a 'real-life' video from Mike Bromberg: