The nifty fifty (f/1.8) is a good deal at $100, but I've never tried to use it for a wedding. I prefer the 50mm f/1.4. (I shoot all primes at weddings. 20mm f/2.8, 24mm f/1.4, 50mm f/1.4, 100mm f/2) and one zoom (70-200 f/4 IS).
Daniel
Do you use multiple cameras or just change lenses a lot?