Laxmom,I've crotched rugs for my very odd sized bathroom.They were out of the cotton yarn.(4 strands). The pattern had raised "bumps" and they feel like I'm getting a little foot massage when I stand on it.Made some for my mom too. Good thing is I got to choose and match the colors I wanted.
Also have used left over yarn to make-I know this may sound strange-floor mats for my van.This way I get to wash my mats and they have a sort of home-i-ness about them.I took a paper bag,placed it in the areas around the pedals and made my self a template.Also made long ones for the seats in the back.Got tired of mud,sand etc.from dog and children.Since the children are now adults and on their own,and my mats are doing just fine,I can say they wear well.
I got the pattern book years ago but I'm sure something is still around.You could just make something up too.