V-belts and flat belts are still used very often. The classical profile (Z,A,B,C) and the small profile (SPZ, SPA, SPB, SPC) are the most common profiles. They are available in "raw egde" where the v-belt is not cogged. The raw egde belt, eg. XPA can transmit more power, because the friction is higher than in the cogged versions.
The developments of the last years are, banded v-belts, where the belts are connected at the backside of the belt. Also poly-V belts are relatively new. All these belt transmissions, are called force in transmissions, because the tensionforce in the belt is determening the transmittable power.
Belt transmissions are often used when the dampening carakteristic is usefull. When more belts are used to run in a pair, the length-stability can be important.
When determining a v-belt drive, you should take care for the tensionforces and the diameters of the pulleys. The bigger the pulley diameters are chosen, the higher the belt speed the lower will the required belttension be.