Let your feet do the work?
I wrote this post a while back. The content can still be relevant but the information I've linked to may not be available.
The BBC reports that Microsoft are developing a foot pad that will enable you to perform common computer actions using your feet. Apparently, the 'double stamp' is a popular action that enables you to delete spam emails.
It's fair to say that I am not entirely convinced that this will catch on – but the amount of spam emails will mean regular exercise for some people!