This is a sensational tool for web developers and content creator.
Tingelets are a set of bookmarklets that you can place in your browsers bookmark bar. When clicked, they highlight a certain tag or set of tags in a specific color or background tile. They are very handy for quickly looking at web layouts in different browsers. You can either highlight tags directly or type in a tag, id or class name to highlight the matching element(s).
Tingelets are not aiming to replace tools like Firebug or Style xope. They are a nice addition when you want to get a quick overview of a web layout and to spot rendering quirks in different browsers.