beamer dark theme

Personally, I don't like presentations with dark backgrounds since my eyes get tired too soon, but that's just a personal opinion. The beamer theme matrix shows a number of color themes that will give you dark backgrounds; for example:

\documentclass{beamer}
\usetheme{Warsaw}
\usecolortheme{beetle}

\begin{document}

\begin{frame}
\frametitle{Test Frame}
text
\end{frame}

\end{document}

or

\documentclass{beamer}
\usetheme{Warsaw}
\usecolortheme{fly}

\begin{document}

\begin{frame}
\frametitle{Test Frame}
text
\end{frame}

\end{document}

If you want to design your own, you can for example look at those color themes (they are in the directory /usr/local/texlive/2011/texmf-dist/tex/latex/beamer/themes/color in a typical TeX Live2011 installation) and make your adjustments. For example, here'sa variation on the fly color theme, but with a black background, as requested:

\documentclass{beamer}
\usetheme{Warsaw}

\setbeamercolor{normal text}{fg=white,bg=black!90}
\setbeamercolor{structure}{fg=white}

\setbeamercolor{alerted text}{fg=red!85!black}

\setbeamercolor{item projected}{use=item,fg=black,bg=item.fg!35}

\setbeamercolor*{palette primary}{use=structure,fg=structure.fg}
\setbeamercolor*{palette secondary}{use=structure,fg=structure.fg!95!black}
\setbeamercolor*{palette tertiary}{use=structure,fg=structure.fg!90!black}
\setbeamercolor*{palette quaternary}{use=structure,fg=structure.fg!95!black,bg=black!80}

\setbeamercolor*{framesubtitle}{fg=white}

\setbeamercolor*{block title}{parent=structure,bg=black!60}
\setbeamercolor*{block body}{fg=black,bg=black!10}
\setbeamercolor*{block title alerted}{parent=alerted text,bg=black!15}
\setbeamercolor*{block title example}{parent=example text,bg=black!15}


\begin{document}

\begin{frame}
\frametitle{Test Frame}
\framesubtitle{Test Frame}
Test
\begin{enumerate}
\item Test
\end{enumerate}
\begin{block}{Test}
Test
\end{block}
\end{frame}

\end{document}