With the addition of the Safari Extensions Gallery to Apple's website, TUAW will be highlighting extensions that we think are special, useful, or just plain fun.
gleeBox will certainly delight keyboard jockeys, as it replaces many browser-based tasks you'd typically complete by mousing around with super-easy hotkey commands. For example, you can call on URLs by hitting the proper command and typing the name of the URL in the resulting overlay. In fact, it'll recognize what you're typing so you needn't type the whole thing.
gleeBox also executes bookmarklets in the same way, so you can add a long article to Instapaper, for example, without ever touching the mouse.
It's not for everyone, but those who like keeping their hands on the keyboard at all times should find it useful.