The MarshGuard, created by Jason Marsh, is a race oriented minimally designed guard that you can apply easily to your bike with zip ties. The guards are made from a recycled material and are incredibly tough and resilient to all the harsh and demanding conditions of mountain biking. Besides deflecting mud from the riders face, the positioning of the guard helps to protect fork stanchions and their seals. This extends the service intervals of your forks.
MarshGuards are a well researched simple solution, they are very light (at 21 grams), look cool, and are made with aerodynamics in mind.