The following live templates are available for the tab completion:

Template	Expansion
item	\begin{itemize} \item | \end{itemize}
enum	\begin{enumerate} \item | \end{enumerate}
i	\item
tikz	\begin{tikzpicture} | \end{tikzpicture}
fig	\begin{figure} | \caption{caption} \label{fig:label} \end{figure}
center	\begin{center} | \end{center}
align	\begin{align*} | \end{align*}
eq	\begin{equation*} | \end{equation*}
eqn	\begin{eqnarray*} | \end{eqnarray*}
verb	\begin{verbatim} | \end{verbatim}
sec	\section{name}\label{sec:label} |
ssec	\subsection{name}\label{sec:label} |
sssec	\subsubsection{name}\label{sec:label} |
frame	\begin{frame} \frametitle{title} | \end{frame}
it	\textit{text}|
bf	\textbf{text}|
tt	\texttt{text}|
emph	\emph{text}|
tab	\begin{tabular}{|c|} | \end{tabular}
env	\begin{env}opt | \end{env}

If you want to add more templates you can put them into JLatexEditor.jar/data/codehelper/tabCompletion.xml. But be careful: The file is automatically overwritten by the next update. But we are working on a persistent solution.