One set I've been testing to pretty good success is the following:
Scizor
@ Life Orb
Adament
Technician
IVs: HP: 29, Atk: 28, Def: 28, Spe: 28, SpAtk: 31, SpDef: 31 (HP Elec)
Or HP: 28, Atk: 29, Def: 29, Spe: 28, SpAtk: 30, SpDef: 31 (HP Grass)
Or: HP: 29, Atk: 29, Def: 29, Spe: 28, SpAtk: 31, SpDef: 31 (HP Ice)
Evs: Atk: 180, Spe: 72 SpAtk: 252
Moves:
Swords Dance
Bullet Punch
Quick Attack
Hidden Power (Electric or Grass or Ice, base 60)
Comment: A very, very strange set at first glance. Why use Scizors crappy base 55 SpAtk AND invest tons of EVs? Well, this spread gives about 209 SpAtk (depending on IVs) and Hidden Power Electric or Grass with Base 60 power (90 with Technician). Why? To decimate Gyarados (dealing 302 to 355 damage, easily OHKOing with Stealth Rocks on max HP, min SpDef) and Swampert (dealing 331 to 389 damage, about 26% to OHKO with Stealth Rocks on min SpDef investment). HP Electric can 2HKO a Skarmory too, and with the given EVs, you outspeed the common defensive version so you can nail it on the switch and finish it next turn. Both super effective HPs can 2HKO Starmie.
HP Ice easily OHKOs Salamence, Gliscor and Flygon but you'll have to catch the dragons on the switch or you'll eat fire.
Bullet Punch and Quick Attack pick off anything standing after the specific Hidden Power.
The idea here is bring Scizor in later than usual, after you know their team well. If you know which counter is coming, use the Hidden Power and destroy it, eliminating what is likely their last Scizor counter and sweep.
Other Hidden Power ideas are Ground (for Heatran, who is OHKO'd with Stealth Rock, assuming it's not packing a Shuca Berry and isn't the Rest-Talk set) or Fire (for Forretress or Scizor), it really depends who your team can take down easily. Note, you don't need the speed EVs if you don't fear Skarmory but don't be afraid to add more speed EVs or even try a different personality to help with SpAtk (for some 2HKOs) if you really fear a counter.
You absolutely need Stealth Rocks and if you have Spikes (Toxic or not) all the better. It's a bit of a gimmick but extremely surprising and effective if you can predict. You can really nail some of Scizor's biggest counters with base 90 special attacks.
PS: Yes, Natural Gift is similar but it's a one shot deal and requires a berry
IVs for Hidden Power can be found here:
http://www.smogon.com/dp/articles/technician_hidden_powers