This little round was used for years by the USSR and it's allies. It's been around since 1930, and has been used in several hand guns and submachine guns such as the TT-33, CZ-52, and the PPD-40 submachine gun. It was based off the 7.63x25mm Mauser cartridge (which was used in the Mauser C-96 pistol) that was gaining popularity at the time.
The round uses a 30 caliber bullet (.308 -.309) which typically weighs 85-90 gr, and is fired at velocities of 1200-1700 FPS. Lighter bullets can be pushed past 2000 FPS. The 7.62 Tok is also known for it's accuracy, and it's long range (compared to other handguns).
Personally, I'd like to see a lightweight semi auto rifle chambered in this round, and some ballistic tip/soft point bullets made for it as well. It would make a decent small game gun.