Hewlett Fine/Medium Diamond Sharpening Plate
This and a jasper whetstone is pretty much what I use to sharpen knives these days. It is compact and lightweight, won't break if you drop it, requires only clear water (or spit in a pinch) to use, lasts a real long time and sharpens faster than natural or synthetic stone. These are fine (1800 grit) on one side and medium (600 grit) on the other. Highly recommended. Comes with a plastic protective sleeve.