okay, i just went to walmart and saw this down the aisle where the dish soap and sponges are. the sonic scrubber? seriously? where has this thing been all my life? of course i bought one (and the set of 4 attachments) immediately. it's like 10 bucks. and there's already batteries in it. grout, beware. if you go to the website, they have all kinds of other attachments, etc. so check it out, already! now i have to go and attack the corners and crevices in my shower. what fun.
picture via sonic scrubber