It's all well and good saving weight off the wheels if you're an XC racer, but saving too much weight often ends up with wheels not up to the abuse they're likely to recieve. I like to use kit that's as light as I can get away with (no point in carrying around unecessary weight!), but feel going for Mavic 717's, or Stans Olympics or DT4.2 rims etc. would be too much of a strength compromise for me.
So for me:
Front hub: Maverick 24mm, 250g (but that includes the axle, so effectively remove approx 50 to 60g for fair comparison to a "normal" hub)
Rear hub: Shimano XT M775 disc, quoted 330g
Read skewer: XT, approx 70g
Rims: Mavic XM819 UST (claimed 465g each, more like about 510g in reality)
Spokes: 64 DT comp 2.0/1.8, approx 370g
Nipples: 64 Brass 14mm, approx 60g
Tyres: Currently 2" Bonty Mud X, approx 550g each
Sealant: Approx 80ml of Stans sealant in each wheel
Pair without tyres = Approx 2.1kg including rear skewer and front axle.
I'm happy with that, considering the 819's are a flipping stiff rim, and can take pretty much any abuse I can give them. Certainly a weaker rim wouldn't last long enough I think, besides I like UST. OK, I could save 50g off the rear hub weight easily by going to a Hope Pro 2, but the XT was Â£35, a Hope Pro 2 is Â£120, Â£85 extra wasn't worth the weight saving I felt. Again, could go for lighter spokes, but DT Revolutions are too flexy really, and I wasn't going to spend upwards of Â£1 per spoke for DT super comps when normal DT comps are only about 25g per wheel heavier, and they're less than half the price. And brass nipples cos I hate ally ones!