When you're working with wood, they say you should always measure twice and cut once. But there's no mention of ensuring the pencil line you draw to make that single cut is as straight as possible. A company called Prazi believes you can actually create a straighter, truer line with a utility knife instead of a carpenter's pencil, so it has created a replacement blade made of graphite that works like a pencil.
The Accutrax pencil blades are compatible with any standard utility knife, and they can be easily swapped for regular blades when you need to slice—they also, apparently, produce a thin accurate line without the need for sharpening. They will wear out eventually, however, so despite the misleading product shot, they are actually sold in sets of three for $10. Just remember: It's probably a bad idea to send your kid off to school with one of these in their pencil case. [Prazi USA via Werd]