This is an excellent question, BlueCaspar! I don't have quite the same situation, but do have a job that is driving me right over the edge, NEED to find something else and have been wondering the exact same thing... WHAT to do! I have such scattershot skill set and most experience in jobs I can no longer handle, not to mention not paying nearly enough to live on (which, being divorced, I need to be able to do now). Ack!
This sounds like a good one. Yours undoubtedly pays better, but is similar in interaction level to working picking or packing in a warehouse, which I have done (though it was 25 years ago...). Guess another brainstormer would be something one could get into that wouldn't necessarily require experience. It's very frustrating to know you would be able to do something, but can't get in to prove it (especially in light of the current economy...).

I've not done the janitor thing, BlueCaspar, though at one point I did have a cleaning business (just me, so no employees to deal with, because I just couldn't handle that), which is kind of a twist on that, though probably a bit more appealing. Did both residential and construction cleaning (which you can charge more for). Yes, there is the procuring clients bit, but if you can get a couple, are good at the work, and trustworthy, word of mouth definitely helps pretty well eliminate having to turn them up cold, which saved my bacon, because that scares the crap out of me(!)

Very curious to see what others might suggest.