Dude, ZIP XLS WTF?
         

One of the rocket scientists over at Spam Central has plumbed new depths in the search for novel ways to deliver their stock spam. They've started sending Excel spreadsheets ... compressed as zip archives. The documents promote EXMT.PK and are stylistically similar to other Excel spams promoting the same company's stock on the Frankfurt exchange (sent only to German addresses, we've only seen examples of these in backscatter).

Aside from the fact that zip attachments are 'delete on sight' for 99.99% of the anti-spam and anti-virus solutions out there, I really can't see anything wrong with this idea at all.
         

http://www.spamnation.info/blog/archives/2007/07/seriously_dude_zip_xls_wtf.html