We investigate femtosecond optical parametric oscillators (OPO's) based on short pieces of microstructure fiber that generate sub-picosecond pulses with record average output power (50 mW) and >200 nm of wavelength tunability (yellow to near-IR). Signal and conjugate (idler)fields spanning an octave are also demonstrated. These systems can operate with a wide range of microstructure fibers, pump laser wavelengths and pulse durations, and our analysis shows that in terms of wavelength tunability and output power using short (less than a few cm's) optical fibers leads to performance that is superior to that with longer lengths.