Put the glass over the top of the spider, put a piece of card underneath the glass, and deposit the spider outside.

A glass, huh? I hadn't thought of that. I just grab it with a piece of paper towel, but that would be much too risky if any of the spiders in my area were venomous. (...at least, I don't think they are. Possibly this would be a good time to Google something like "spiders of the great lakes region".)