Q:

How to rotate a TikZ text node depending on its content?

I would like to rotate a TikZ text node by a degree that depends on the content length. So a text node with 20 characters should be rotated e.g. 20*0.1 = 2 degree, a text node with 100 characters for 100*0.1 = 10 degree. It does not matter if whitespace influences this or not.
Is it possible to do that somehow automatically, or do I need to count letters manually?

A:

This is an approximation. First, calculate the average character width, then create a new command to add the node with the rotation set to <length of node text>/<average character length> * 0.1. 
\documentclass[border=2mm]{standalone}
\usepackage{tikz}
\pgfmathsetmacro\characterlength{width("abcdefghijklmnopqrstuwxyz")/26}
\newcommand{\rotatenode}[3][]{\node [rotate=width("{#3}")/\characterlength*0.1,#1] at (#2) {#3};}
\begin{document}
\begin{tikzpicture}
\rotatenode[draw]{0,1}{abcdefghijklmnopqsrt}
\rotatenode[draw,red]{0,2}{abcdefghijklmnopqsrtabcdefghijklmnopqsrtabcdefghijklmnopqsrtabcdefghijklmnopqsrtabcdefghijklmnopqsrt}
\end{tikzpicture}
\end{document}

