Charge Spoon
Cheap/Light/Strong, pick all 3!
Ok, it's not THE lightest saddle, but at 260g for a cromo railed saddle, it's lighter than a lot of ti railed saddles out there. OK, it's not gonna find its way onto an XC race bike I doubt, but 260g is plenty light enough for most of us.
They're also pretty comfortable, which is important obviously. Oh, and they're a lot easier to move around on than most other saddles I've tried, which is important in the "being able to get your arse off the back of the saddle" moments to ride steep sections etc, which is where my SDG Bel Air (though it's very comfortable) sucks arse, cos it's not very easy to get on/off it in a hurry.