Here is a must know list of libraries, if you want to use Python for data mining:

NumPy  stands for Numerical Python. Most commonly used for ndimensional arrays, random number operations

SciPy  stands for Scientific Python. Can be used for Fourier transforms, Linear Algebra

Matplotlib  provides MATLAB like plotting functionality in Python

Pandas  brings DataFrame in Python. This should provide you easy ways to aggregate and Pivot data

Scikitlearn  Most useful library for Machine Learning on Python

Regular Expressions  You will use it for data munging and pattern extraction
Additional libraries which you might find useful:

BeautifulSoup  for crawling web pages in case you need to extract data from the web

Pattern  for NLP, machine learning and network analysis

Statsmodels  for Descriptive stats, hypothesis testing

NetworkX & igraph  for graph based data manipulation

os  for using os inside Python applications

urllib  to open web pages and perform file operations

NLTK  Natural Language ToolKit for Natural Language Processing
You can read more about these libraries here: http://www.analyticsvidhya.com/blog/2014/07/babystepslibrariesdatastructure/
This should be a good list to learn and explore
Regards,
Kunal