Learning
Python & programming
Snytax: Learn Python the Hard Way (by Zed Shaw)
newcoder.io: Learning more Python via projects - an excellent next step; in this tutorial series you will be building real-world apps while learning more of Python. You will play with, Data Visualization, APIs, Web Scraping, Networks, GUI.
Tools
Git
git - the simple (visual) guide by R. Dudler - a minimalistic yet sufficient intro into git in a rather simple and visual way. Cons: too little about reslving conflicts and tools for merging. I’d also prefer if it recommended rebasing over merging. Has also a git cheatsheet.
An interactive one-page git cheatsheet highlighting the differences between stash, workspace, index, local repository, and upstream repository (a.k.a. origin)