Flesh out examples included in docstrings
```
.../pandas$ nosetests -v --with-doctest -I .*test
/.../.virtualenvs/myenv/local/lib/python2.7/site-packages/scikits/statsmodels/__init__.py:2: UserWarning: scikits.statsmodels namespace is deprecated and will be removed in 0.5, please use statsmodels instead
  warnings.warn('scikits.statsmodels namespace is deprecated and will be '
/.../.virtualenvs/myenv/local/lib/python2.7/site-packages/scikits/statsmodels/regression/__init__.py:2: UserWarning: scikits.statsmodels namespace is deprecated and will be removed in 0.5, please use statsmodels instead
  warnings.warn('scikits.statsmodels namespace is deprecated and will be '
Doctest: pandas.compat.scipy.percentileofscore ... ok
Doctest: pandas.compat.scipy.rankdata ... FAIL
Doctest: pandas.compat.scipy.scoreatpercentile ... FAIL
Doctest: pandas.core.algorithms.quantile ... ok
Doctest: pandas.core.common.iterpairs ... FAIL
Doctest: pandas.core.common.split_ranges ... ok
Doctest: pandas.core.format.EngFormatter.__call__ ... FAIL
Doctest: pandas.core.frame.DataFrame.__init__ ... FAIL
Doctest: pandas.core.frame.DataFrame.apply ... FAIL
Doctest: pandas.core.frame.DataFrame.combine_first ... FAIL
Doctest: pandas.core.frame.DataFrame.merge ... FAIL
Doctest: pandas.core.frame.DataFrame.pivot ... FAIL
Doctest: pandas.core.frame.DataFrame.reindex ... FAIL
Doctest: pandas.core.frame.DataFrame.reindex_axis ... FAIL
Doctest: pandas.core.frame.DataFrame.set_index ... FAIL
Doctest: pandas.core.frame.DataFrame.sort ... FAIL
Doctest: pandas.core.frame.DataFrame.sort_index ... FAIL
Doctest: pandas.core.frame.DataFrame.stack ... FAIL
Doctest: pandas.core.frame.DataFrame.to_excel ... FAIL
Doctest: pandas.core.frame.DataFrame.unstack ... FAIL
Doctest: pandas.core.frame.DataFrame.xs ... FAIL
Doctest: pandas.core.generic.PandasObject.groupby ... FAIL
Doctest: pandas.core.groupby.NDFrameGroupBy.transform ... FAIL
Doctest: pandas.core.groupby.SeriesGroupBy.aggregate ... FAIL
Doctest: pandas.core.groupby.SeriesGroupBy.transform ... FAIL
Doctest: pandas.core.index.Index.diff ... FAIL
Doctest: pandas.core.index.Index.get_indexer ... FAIL
Doctest: pandas.core.index.MultiIndex.get_indexer ... FAIL
Doctest: pandas.core.indexing._SeriesIndexer ... FAIL
Doctest: pandas.core.panel.WidePanel.transpose ... FAIL
Doctest: pandas.core.panel.panel_index ... FAIL
Doctest: pandas.core.reshape._Unstacker ... FAIL
Doctest: pandas.core.reshape.lreshape ... FAIL
Doctest: pandas.core.reshape.melt ... FAIL
Doctest: pandas.core.series.Series.map ... FAIL
Doctest: pandas.core.series.Series.rename ... FAIL
Doctest: pandas.core.series.Series.sort_index ... FAIL
Doctest: pandas.core.series.Series.unstack ... FAIL
Doctest: pandas.core.strings.StringMethods ... FAIL
Failure: ImportError (No module named httplib2) ... ERROR
Doctest: pandas.io.data.Options ... FAIL
Doctest: pandas.io.data.Options.get_call_data ... FAIL
Doctest: pandas.io.data.Options.get_options_data ... FAIL
Doctest: pandas.io.data.Options.get_put_data ... FAIL
Failure: ImportError (No module named httplib2) ... ERROR
Doctest: pandas.io.pytables.HDFStore ... FAIL
Doctest: pandas.io.pytables.get_store ... FAIL
Doctest: pandas.io.sql.sequence2dict ... ok
Failure: ImportError (No module named util) ... ERROR
Failure: ImportError (No module named rpy2.robjects.packages) ... ERROR
Failure: ImportError (No module named util) ... ERROR
Failure: ImportError (cannot import name WLS) ... ERROR
Doctest: pandas.tools.merge.merge ... FAIL
Doctest: pandas.tools.merge.ordered_merge ... FAIL
Doctest: pandas.tools.pivot.crosstab ... FAIL
Doctest: pandas.tools.pivot.pivot_table ... FAIL
Doctest: pandas.tools.plotting.boxplot_frame_groupby ... FAIL
Doctest: pandas.tools.plotting.parallel_coordinates ... FAIL
Doctest: pandas.tools.plotting.scatter_matrix ... FAIL
Doctest: pandas.tools.tile.cut ... FAIL
Doctest: pandas.tseries.period.Period.strftime ... FAIL
Doctest: pandas.tseries.period.PeriodIndex ... FAIL
Doctest: pandas.util.compat._Counter ... ok
Doctest: pandas.util.compat._Counter.__add__ ... ok
Doctest: pandas.util.compat._Counter.__and__ ... ok
Doctest: pandas.util.compat._Counter.__init__ ... ok
Doctest: pandas.util.compat._Counter.__or__ ... ok
Doctest: pandas.util.compat._Counter.__sub__ ... ok
Doctest: pandas.util.compat._Counter.elements ... ok
Doctest: pandas.util.compat._Counter.most_common ... ok
Doctest: pandas.util.compat._Counter.update ... ok
Doctest: pandas.util.counter.Counter ... ok
Doctest: pandas.util.counter.Counter.__add__ ... ok
Doctest: pandas.util.counter.Counter.__and__ ... ok
Doctest: pandas.util.counter.Counter.__init__ ... ok
Doctest: pandas.util.counter.Counter.__or__ ... ok
Doctest: pandas.util.counter.Counter.__sub__ ... ok
Doctest: pandas.util.counter.Counter.elements ... ok
Doctest: pandas.util.counter.Counter.most_common ... ok
Doctest: pandas.util.counter.Counter.subtract ... ok
Doctest: pandas.util.counter.Counter.update ... ok
...
Ran 81 tests in 4.671s

FAILED (errors=6, failures=52)
```

From the Messages (not included in the code snippet above) one can see that most errors result from ImportErrors, so maybe the problem is only that the imports are not in the docstring.
