Center-It Drill Jig
Rockler 3/8'' Dowel Drilling Jig Kit. Rockler.com woodworking tools
Cross-dowel drill jig.
Picture of How To Drill Straight Holes with a Hand Drill (Using Lego)
diy Shelf Pin Drilling jig. Cheap and easy alternative to expensive manufactured jigs -- and it works way better too!
diy Shelf Pin Drill Jig
Simple jig for drilling holes in rods and tubes.
Straight-Up Drill Guide
Vertical Drilling Jig - Drill Tips, Jigs and Fixtures | WoodArchivist.com
DIY Jig for drilling Shelf Pin Holes