I was looking over the analysis of some OU pokemon recently, and I'm sure that it was mentioned that Garchomp's special attack is usable (BS 80).
How interesting.
But then I saw that Chomp had no Choice Specs option. And I thought to myself, I wonder if it could run one...
Garchomp @ Choice Specs
Ability: Sand Veil
Nature: Timid
DRACO METEOR
EARTH POWER
FLAMETHROWER
DRAGON PULSE/SURF/OUTRAGE/HIDDEN POWER
EVs: 252 SAtk, 236 Spd, 20 HP
Garchomp got reliable ground-type STAB in Platinum, via the move tutors. Earth Power is now available and the old excuse of 'no ground moves' is no longer available.
As for the other moves, Draco Meteor is hideously overpowered STAB and its recoil is no problem for a Choice Specs pokemon, who has to switch many times anyway. Flamethrower takes care of everything that resists its STAB combination (ie. Skarmory and Bronzong).
The last moveslot is much a filler. Dragon Pulse is more reliable than Draco Meteor and is invaluable in lategame for a SpecsMence. Surf is there to hit stuff that you may be worried about, or may not be, such as Rhyperior and Gliscor. Outrage is there because... well, for some inexplicable reason its suddenly a good move, but on the serious side it's a physical attack for use on physical walls. Feel free to adjust the EVs to accomodate a physical attack. Hidden Power is for 4x weak pokemon you may want coverage against, for example HP Electric for Gyarados.
The Nature and EVs, I think, allow you to outspeed all +Speed Nature Base 100 pokemon while maintaining some degree of bulk.
Reasons to use this over SpecsMence? It's faster, has STAB Earth Power and nearly every move that SpecsMence can use (with Earth Power over HP ground and Surf over Hydro Pump) as well as some unique to it.
However, it does not have Salamence's great Special Attack Stat, and is rather inferior to every other Chomp incarnation you see. But the surprise factor can knock an opponent off guard... until, of course, you realise that the opponent just brought in Blissey, and you must flee in terror.