Off the top of my head, here are the five stupidest things you can do with your resume:
1. Leave off your CELL phone number and/or email address
2. Send it to several headhunters at once, filling in all their names in the "To" line
3. Naming your resume "Resume" instead of using your first and last name
4. Lie about ANYTHING. Have resumes in circulation that say something else
5. Using the same version for all the jobs you apply for, rather than taking the time to modify it to better reflect the requirements at the other end.