How to refer to the corner of a node?

Question

Is there a node suffix for the corners of a node?

I'd like the brace in this example to go from the lower-left corner of the first box to the lower-right corner of the last.

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes,patterns,decorations.pathreplacing}
\begin{document}
    \tikzstyle{frame} = [rectangle, draw, fill=blue!20,
        text width=4em, text centered, minimum height=3em, node distance=3cm]
    \begin{tikzpicture}
        \node [frame] (f1) {$f_1$};
        \node [frame, right of=f1] (f2) {$f_2$};
        \node [frame, right of=f2] (f3) {$f_3$};
        \draw [decoration={brace,mirror},decorate] (f1.center) -- (f3.center);
    \end{tikzpicture}
\end{document}

Answer 1

Use south east and south west anchors (details on page 308 of TikZ manual):

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes,patterns,decorations.pathreplacing}
\begin{document}
    \tikzstyle{frame} = [rectangle, draw, fill=blue!20,
        text width=4em, text centered, minimum height=3em, node distance=3cm]
    \begin{tikzpicture}
        \node [frame] (f1) {$f_1$};
        \node [frame, right of=f1] (f2) {$f_2$};
        \node [frame, right of=f2] (f3) {$f_3$};
        \draw [decoration={brace,mirror},decorate] (f1.south west) -- (f3.south east);
    \end{tikzpicture}
\end{document}

Result: