The tikz-3dplot package totally rocks. I just drew my picture in the x-y-plane and rotated it then. The only caveat is that rectangle does not work any more, one has to supply all four corners by hand.

\begin{tikzpicture}[scale=2]
\tdplotsetmaincoords{45}{200}
\begin{scope}[tdplot_main_coords]
\draw (0, 0) -- (5, 0) -- (5, 5) -- (0, 5) -- cycle;
\node[below right] at (0, 5) {$\R^3$};
\begin{scope}
\clip (0, 0) -- (5, 0) -- (5, 5) -- (0, 5) -- cycle;
\fill[opacity=20, color=black!20] ($(1, 1)+(45:3)+(0.5, 0)$) arc (0:360:0.5);
\begin{scope}[->, thick]
\draw (1, 1) -- ++(60:3) node[midway, below] {$t$};
\draw (1, 1) -- ++(100:2.5) node[midway, right] {$t_0$};
\draw (1, 1) -- ++(30:3.5) node[midway, below] {$t_1$};
\draw (1, 1) -- ++(0:1.5) node[midway, above] {$t$};
\end{scope}
\draw (4, 1) arc (0:360:3);
\draw (3.5, 1) arc (0:360:2.5);
\draw (4.5, 1) arc (0:360:3.5);
\draw (2.5, 1) arc (0:360:1.5);
\end{scope}
\draw[thick, ->] (5, 5, 0) -- ++(0, 0, 2) node[sloped, midway, above] {Zeitachse};
\end{scope}
\end{tikzpicture}
tikz-3dplotpackage could be useful. – Manuel Dec 23 '12 at 22:35