I have small graph in my presentation (I have to). To adjust the size of the legend, I have to use very small legend. But \tiny is not enought.
Here is a MWE :
\documentclass{beamer}
\usepackage{etex}
\usepackage[frenchb]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8x]{inputenc}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\usepackage{epstopdf}
\usepackage{tikz}
\usepackage{circuitikz}
\usepackage{pstricks}
\usepackage{array}
\usepackage{graphicx}
\usepackage{filecontents}
\begin{filecontents}{data.dat}
x,y
1,2
2,3
3,4
\end{filecontents}
\begin{document}
\begin{frame}
\begin{tikzpicture}
\begin{axis}[
legend style={font=\tiny},
xlabel={x},
ylabel={y},
width=4cm, height=3cm,
ymin=0,
xmin=0,
xmajorgrids, xminorgrids, ymajorgrids,
]
\addplot table [col sep=comma]{data.dat};
\addlegendentry{Test Test Test};
\end{axis}
\end{tikzpicture}
\end{frame}
\end{document}
Giving this :

