It’s difficult to create tables in LaTeX, especially if some columns are calculated. Excel2LaTeX allows you to transform the current selection from Excel to Latex. Most of the formatting will be kept (bold, italic, border lines, multicolumn cells, etc.). The LaTeX code can be copied to the clipboard or saved as a LaTeX file, which then can be included in an existing LaTeX document using the \input command.
Download: Excel2Latex 2.0