redis-py
The Python interface to the Redis key-value store.
Project Source: https://github.com/andymccurdy/redis-py

mongo-python-driver
The PyMongo distribution contains tools for interacting with MongoDB database from Python.
Project Source: https://github.com/mongodb/mongo-python-driver
Project Homepage: http://api.mongodb.org/python/

sandman
Sandman lets you interact with your database through a simple website and takes seconds to setup.
Project Source: https://github.com/jeffknupp/sandman Project Homepage: http://www.sandman.io/

peewee
A small, expressive orm -- supports postgresql, mysql and sqlite.
Project Source: https://github.com/coleifer/peewee
Project Documentation: http://peewee.readthedocs.org/en/latest/

dataset
Easy-to-use data handling for SQL data stores in Python with support for implicit table creation, bulk loading, and transaction.
Project Source: https://github.com/pudo/dataset
Project Homepage: https://dataset.readthedocs.org/en/latest/

redis-rdb-tools
Rdbtools is a parser for Redis' dump.rdb files. The parser generates events similar to an xml sax parser, and is very efficient memory wise.
Project Source: https://github.com/sripathikrishnan/redis-rdb-tools

swift
A distributed object storage system designed to scale from a single machine to thousands of servers.
Project Source: https://github.com/openstack/swift
Project Homepage: http://openstack.org/

BayesDB
A Bayesian database table for querying the probable implications of data as easily as SQL databases query the data itself.
Project Source: https://github.com/mit-probabilistic-computing-project/BayesDB
Project Homepage: http://probcomp.csail.mit.edu/bayesdb/

mongoengine
A Python Object-Document-Mapper for working with MongoDB.
Project Source: https://github.com/MongoEngine/mongoengine
Project Homepage: http://mongoengine.org/

redis-faina
A query analyzer that parses Redis' MONITOR command for counter/timing stats about query patterns.
Project Source: https://github.com/Instagram/redis-faina

PyMySQL
Pure-Python MySQL Client.
Project Source: https://github.com/PyMySQL/PyMySQL

wal-e
WAL-E is a program designed to perform continuous archiving of PostgreSQL WAL files and base backups.
Project Source: https://github.com/wal-e/wal-e

twissandra
Twissandra is an example project, created to learn and demonstrate how to use Cassandra.
Project Source: https://github.com/twissandra/twissandra

asyncmongo
An asynchronous library for accessing mongo with tornado.ioloop.
Project Source: https://github.com/bitly/asyncmongo

pycassa
Python Thrift driver for Apache Cassandra.
Project Source: https://github.com/pycassa/pycassa
Project Documentation: http://pycassa.github.io/pycassa/

sqlalchemy
The Python SQL Toolkit and Object Relational Mapper.
Project Source: https://github.com/zzzeek/sqlalchemy

dex
Index and query analyzer for MongoDB: compares MongoDB log files and index entries to make index recommendations.
Project Source: https://github.com/mongolab/dex

pgtune
PostgreSQL configuration wizard.
Project Source: https://github.com/gregs1104/pgtune
Project Homepage: http://pgfoundry.org/projects/pgtune/

pony
An object-relational mapper.
Project Source: https://github.com/ponyorm/pony
Project Homepage: http://ponyorm.com/

kule
Kule is a REST interface for MongoDB.
Project Source: https://github.com/fatiherikli/kule

mongokit
MongoKit framework try to keep its simplicity when you manage mongodb in python.
Project Source: https://github.com/namlook/mongokit

bulbs
A Python persistence framework for graph databases like Neo4j, OrientDB and Titan.
Project Source: https://github.com/espeed/bulbs
Project Homepage: http://bulbflow.com/