Many things could be improved in NumPy: * make it easier to implement and deploy custom dtypes, fix the time-related dtype * support for ragged arrays *

Many things could be improved in NumPy: * make it easier to implement and deploy custom dtypes, fix the time-related dtype * support for ragged arrays * consolidate internals, especially around ufuncs I also think some non trivial part of pandas lowest levels belong to NumPy, though I have not thought very deeply about that one: support for missing value, some kind of indexing, etc...