Keyboard Font for LaTeX

You can use the menukeys package which is included in texlive-full.

Example

\documentclass[a5paper,9pt]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage{menukeys}

\begin{document}
 \section{The Manual}
    You can visualize paths \directory{/home/moose/Desktop/manual.tex}
    or menus \menu{View > Highlight Mode > Markup > LaTeX} or key
    press combinations: \keys{\ctrl + \shift + F} is for formatting
    in Eclipse.

    You can also visualize \keys{\tab}, \keys{\capslock}, \keys{\Space}, 
    \keys{\arrowkeyup} and many more.
\end{document}

Rendered

menukeys is included in texlive-full.

The keystroke package is your friend.

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Update:

Sadeq's suggestion could be mimicked very inexpensively by the pgf/tikZ package.

\documentclass[11pt,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{shadows}

\newcommand*\keystroke[1]{%
  \tikz[baseline=(key.base)]
    \node[%
      draw,
      fill=white,
      drop shadow={shadow xshift=0.25ex,shadow yshift=-0.25ex,fill=black,opacity=0.75},
      rectangle,
      rounded corners=2pt,
      inner sep=1pt,
      line width=0.5pt,
      font=\scriptsize\sffamily
    ](key) {#1\strut}
  ;
}

\begin{document}
  The quick brown fox jumps over the lazy dog.
  \keystroke{Strg} The quick brown fox jumps over the lazy dog.
  \keystroke{Ctrl} The quick brown fox jumps over the lazy dog.
  \keystroke{Page $\uparrow$} \keystroke{Esc} \keystroke{F1}
\end{document}

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Another free keyboard font is Linux Biolinum Keyboard. See the following graphic for an example: