Back in Excel 2000 and 2003 you could email a single worksheet from an Excel document, but that was removed for some reason in the more recent versions.  If you miss that feature, or just want more control over what you email, then maybe you should check out this add-on from Ron de Bruin, Microsoft MVP.

You can send the entire workbook, one or multiple worksheets, or even highlighted selections – as both XLS documents or in PDF!

The installation can be a bit tricky, but if you follow the steps and the warnings from Excel, it does work.  On my installation, I had to change a few settings in the Trust Centre.  Once the add-in is installed, it adds a new option to the ribbon menu.  You can always email Ron if you run into problems, or we here at ICS can help you out.