a <b>rat</b>
<img src="http://mkweb.bcgsc.ca/rat/images/raton3700/alex-portrait.jpg">
<img src="http://mkweb.bcgsc.ca/rat/images/raton3700/alex-shoulder.jpg">
they're extremely sweet & they are very clean.
YOU just hafta keep their cage clean for them. once or twice a week the cage needs attended to.
but if you're primarily concerned about having to clean up after a pet, then i suggest the <b>pet rock™</b>
<img src="http://www.portcommodore.com/commodore/pet/petrock.jpg">