Invent With Python - Learn to program Python for free
LibHunt - LibHunt tracks mentions of software libraries on relevant social networks. Based on that data, you can find the most popular projects and their alternatives.
One Month Python - Learn to build Django apps in just one month.
AlternativeTo - AlternativeTo lets you find apps and software for Windows, Mac, Linux, iPhone, iPad, Android, Android Tablets, Web Apps, Online, Windows Tablets and more by recommending alternatives to apps you already know.
Micro Python - Python for microcontrollers
JSter - JSter is a community-driven catalog of the most useful javascript libraries.