Frame - Leave it alone.
Forks - Getting lighter forks (Fatty Rs) will reduce some front end weight makeing th bike easier to control on the back wheel.
Wheels - Wide rims = weight but more stability, slightly narrower rims (mavic ex721) will make your bike lighter and still very strong.
Expensive hubs will also make your bike significantly lighter but I woudnt worry to much about that at this stage to be honest.
Tyres - Michelin Hot s, grippy in the dry, very light, puncture resistance ok-ish.
Cranks/BB - Lighter cranks will also bring the weight down. Middleburns may not be that light but the weight to strength ratio is excelent.
Misc parts (it all adds up) - Ally headset, remove the little springs in your QRs, drill rims, lighter inner tube in the front, disk brakes weight quite a bit and so do maggies so run a V up front, Ti QR levers, ti bash ring.
Bout all that I can thnk of that will drop some weight :(