You'll find those predefined templates in the documentation.
Here are those which are listed in the guide (Chap. 12 Structuring a Presentation: The Local Structure p. 111)
\documentclass{beamer}
\def\mf{
\begin{itemize}
\item Item
\end{itemize}
}
\begin{document}
\frame{
\setbeamertemplate{itemize items}[default]
\mf
\setbeamertemplate{itemize items}[triangle]
\mf
\setbeamertemplate{itemize items}[circle]
\mf
\setbeamertemplate{itemize items}[square]
\mf
\setbeamertemplate{itemize items}[ball]
\mf}
\end{document}

Furthermore you can define your very own items:
\documentclass{beamer}
\def\mf{
\begin{itemize}
\item Item
\end{itemize}
}
\usepackage{tikz}
\usetikzlibrary{shapes.misc}
\begin{document}
\frame{
\setbeamertemplate{itemize items}{\tikz\node[cross out, draw] {good};}
\mf
\setbeamertemplate{itemize items}{$\int$}
\mf
}
\end{document}

pifont
package which includes the environment\begin{dinglist}{number}
wherenumber
can be any of the ones listed here