I use steel foundation stakes to support the formboards for the concrete foundations I build. The stakes are easy to drive, and they have holes drilled in them for driving nails or screws into the form boards.
Problem is, sometimes the concrete traps the stakes.
If you've ever tried pulling a stake out of a 1-ft. thick layer of hardened concrete, you know what I mean. It doesn't matter what kind of form-release agent or recycled motor oil that you apply to the stakes. But I've figured out a solution to the problem. As shown in the drawing at right, I protect the exposed portions of the stakes with sleeves made of PVC pipe. Sure, I have to pay a few bucks for the pipe.