Drill Guide by Frank Ford -- Homemade drill guide fabricated from a thick block of wood. Features an alignment notch to serve as a reference for perpendicularity in two axes. http://www.homemadetools.net/homemade-drill-guide
Water Warden - Drill Guide for Pool Safety Fence Installations - Designed for use during installation of a safety fence, this tools make sure to guide with straight drilling with plus and minus 10 degree angles.
If you’re adding shelf pin holes to an existing piece of furniture or building shelves from scratch, the Shelf Pin Jig is the perfect tool for the job. Unlike other shelf pin guides, the Kreg Shelf Pin Jig features hardened-steel drill guides that ensure precise and straight drilling, so you’ll get level, wobble-free shelves.