You can reset the prescale divide ratio for each timer - by default they are all set to divide-by-128 I think. Also timer0 is set to fast-PWM mode (256 prescaled-clocks per cycle) and timers 1 and 2 are set to phase-correct PWM mode which takes 510 prescaled-clocks per cycle.
Direct register manipulation can be used to reprogram the scaling factors and PWM modes for each timer. timer0 should be left as-is if you want delay(),micros() and millis() to work.
I've some rudimentary notes on the timers at Advanced Arduino: direct use of ATmega counter/timers
(the definitive source is the ATmega328 datasheet though: http://www.atmel.com/Images/doc8161.pdf )