Calculate the date of Easter
Python 2 - 125 120 119 chars

This is Fors's answer shamelessly ported to Python.

y=input()
a=y/100*1483-y/400*2225+2613
b=(y%19*3510+a/25*319)/330%29
b=148-b-(y*5/4+a-b)%7
print(y*100+b/31)*100+b%31+1


Edit:  Changed last line from print"%d-0%d-%02d"%(y,b/31,b%31+1) to save 5 characters.  I would have loved to represent 10000 as 1e4, but that would produce floating point necessitating a call to int.

Edit2:
Thanks to Peter Taylor for showing how to get rid of that 10000 and save 1 character.