Nice looking invoices

This is an old question, but here is a minimal that can display a fairly easy to understand invoice table. Add your logo and tax, if required.

The code automatically auto-increments the item counter and calculates totals.

It uses the fp package for calculations to ensure accuracy. It uses a longtable, as some invoices are rather long.

Here is the MWE. Embellish it with your logo and other details to customize it.

\usepackage{fp}
\usepackage{booktabs}
\usepackage{ragged2e}
\usepackage{longtable}
\newcounter{cnt}
\setcounter{cnt}{0}
\def\inc{\stepcounter{cnt}\thecnt}
\gdef\TotalHT{0}
\newcommand{\product}[3]{%
\inc &#1  &#2   &#3  &\FPmul\temp{#2}{#3}\FPround\temp{\temp}{2}\temp 
%% Totalize
\FPadd\total{\TotalHT}{\temp}%
\FPround\total{\total}{2}%
\global\let\TotalHT\total%
\\ }
\newcommand{\totalttc}{
   \TotalHT  }
\begin{document}
\RaggedRight
\begin{longtable}{cp{4.2cm}rrr}
\toprule
Item   &Description & Price & Qty & Total\\
\midrule
    \product{Computer peripherals}{1000.00}{1}
    \product{Harddisk 2000E}{2000}{1}
    \product{The \TeX book}{100.00}{100}
    \product{Product Four}{5000.00}{1}
    \product{Product Five}{5000.00}{2}
\midrule
    &&&& Total \totalttc\\
\bottomrule
\end{longtable}
\end{document}

Dapper Invoice — A billable-time invoice featuring style over substance

It's light on functionality, but it looks a fair bit more modern than any other LaTeX template I've seen published out there (which is why I took the time to write it). I'm not much of a LaTeX author (the community here helped me a bunch) and I'm not a designer (it borrows heavily from moderncv), but maybe it'll be of use to someone as there's so little out there in LaTeX when you're looking for a billable-time invoice.

Here's an example screenshot:

Take a look at the scrlttr2 package. One of the most versatile letter classes. I made an invoice template based on it and it looked great. Sorry I can't post the source here at the moment (needs editing and my machine can't compile it) but I will briefly comment what I did.

I configured scrlttr2 to get a nice looking business-like letter (KOMA-Script has > 160 pages on scrlttr2). The invoice is embedded in the body of the letter by using the invoice package.