If I'd had this CSS debugging bookmarklet when I was designing this site, I might have ended up with a few less bruises after banging my head on the table in frustration. It outlines each
div and labels it with a colour and a label to indicate its
id. It's really handy, and would also be a useful learning tool when examining other people's sites — in conjunction with the source — to see how they achieve their look.
[via 2lmc spool]