All you need to cut a circle on the band saw is a piece of plywood with a nail driven in to act as a pivot. but this jig is a little more versatile. It's adjustable and easy to detach from your band saw.
I consider the router table one of the unsung heroes of the shop... You can use them to rout edge profiles, cut joinery, edge joint, and more. ChipsFly.com has a new router table that is packed with features that can help you get the most out of your router.