標準っぽいライブラリを列挙する

import sys, string, pydoc, textwrap

w = textwrap.TextWrapper()
w.width = 60
w.subsequent_indent = " " * 18

for key in sorted(filter(lambda key: key[0] in string.lowercase + "_",
                         sys.modules.iterkeys())):
    doc = pydoc.splitdoc(sys.modules[key].__doc__ or "")[0] or "(no document)"
    if len(key) > 14:
        print key
        key = ""
    print "%-14s -- %s" % (key, w.fill(doc))

実行結果:

__builtin__    -- Built-in functions, exceptions, and other objects.
__main__       -- (no document)
_bisect        -- Bisection algorithms.
_codecs        -- (no document)
_codecs_jp     -- (no document)
_heapq         -- Heap queue algorithm (a.k.a. priority queue).
_multibytecodec
               -- (no document)
_sre           -- (no document)
_symtable      -- (no document)
bisect         -- Bisection algorithms.
codecs         -- codecs -- Python Codec Registry, API and helpers.
collections    -- High performance data structures
copy_reg       -- Helper to provide extensibility for pickle/cPickle.
difflib        -- Module difflib -- helpers for computing deltas between
                  objects.
dis            -- Disassembler of Python byte code into mnemonics.
encodings      -- Standard "encodings" Package
encodings._codecs_jp
               -- (no document)
encodings._multibytecodec
               -- (no document)
encodings.aliases
               -- Encoding Aliases Support
encodings.codecs
               -- (no document)
encodings.euc_jp
               -- (no document)
encodings.exceptions
               -- (no document)
encodings.types
               -- (no document)
errno          -- This module makes available standard errno system symbols.
exceptions     -- Python's standard exception class hierarchy.
gc             -- This module provides access to the garbage collector for
                  reference cycles.
heapq          -- Heap queue algorithm (a.k.a. priority queue).
imp            -- (no document)
inspect        -- Get useful information from live Python objects.
itertools      -- Functional tools for creating and using iterators.
linecache      -- Cache lines from files.
marshal        -- (no document)
opcode         -- (no document)
os             -- OS routines for Mac, DOS, NT, or Posix depending on what
                  system we're on.
os.path        -- Common operations on Posix pathnames.
posix          -- (no document)
posixpath      -- Common operations on Posix pathnames.
pwd            -- (no document)
pydoc          -- Generate Python documentation in HTML or text for
                  interactive use.
re             -- Minimal "re" compatibility wrapper.  See "sre" for
                  documentation.
readline       -- Importing this module enables command line editing using GNU
                  readline.
repr           -- Redo the `...` (representation) but with limits on most
                  sizes.
signal         -- This module provides mechanisms to use signal handlers in
                  Python.
site           -- Append module search paths for third-party packages to
                  sys.path.
sre            -- Support for regular expressions (RE).
sre_compile    -- Internal support module for sre
sre_constants  -- Internal support module for sre
sre_parse      -- Internal support module for sre
stat           -- Constants/functions for interpreting results of os.stat()
                  and os.lstat().
string         -- A collection of string operations (most are no longer used).
strop          -- Common string manipulations, optimized for speed.
sys            -- (no document)
textwrap       -- Text wrapping and filling.
thread         -- (no document)
token          -- Token constants (from "token.h").
tokenize       -- Tokenization help for Python programs.
types          -- Define names for all type symbols known in the standard
                  interpreter.
warnings       -- Python part of the warnings subsystem.
zipimport      -- zipimport provides support for importing Python modules from
                  Zip archives.

知らなかったライブラリが結構あるな。

インタラクティブシェルから手っ取り早く知りたいだけならこれでもいい:

>>> import sys, pprint; pprint.pprint(sorted(sys.modules.keys()))