Python 2.7.2
--------------------
0

print 2**38

http://www.pythonchallenge.com/pc/def/map.html
--------------------
1

import string

tran=string.maketrans(string.lowercase[:26],string.lowercase[2:26]+'ab')
'map'.translate(tran)

http://www.pythonchallenge.com/pc/def/ocr.html

--------------------
2

import collections

dic = collections.OrderedDict()
for c in s:
    dic[c] = dic.get(c,0) + 1
avg = len(s)//len(dic)
print(''.join([c for c in dic if dic[c] < avg]))

http://www.pythonchallenge.com/pc/def/equality.html