I've been using the Gilles Berthoud stainless steel fenders from http://www.peterwhitecycles.com/fenders.asp. They aren't as nearly heavy as they sound and are the toughest things going. At 52 bux a pop, not too expensive. If you are considering metal fenders, I'd go with these over aluminum. The aluminum ones are ever so slightly lighter, but will not last nearly so long as aluminum fatigue fails much earlier and fenders are very prone to this, being very thing and getting a lot of vibration.

My current set is 7 years old and going strong. Plenty of commuting, bouncy gravel towpath/trail riding, etc. Another reason these are better than the SKS is that the front fender is a lot longer and will provide better protection for your chain/crank. If you add a mudflap that goes down to an inch or so above the road surface, you can ride in the rain and get no road gunk at all on your shoes and drive train. This saves a lot of hassle for sure.