schedule-free business, conceivable or delusional?

[snoobies]

Sorry about the double post, but it seems this forum section is more geared toward my purpose. I'm not an extreme or very experienced entrepreneur, however I could use some advice from one! Currently I'm employed with the USPS but my schedule can be 6 days a week one week, and 2-3 the next as I am just a relief carrier for regular carriers, a substitute if you will. My wife currently is in school and not working, so everything is dependent on my income - I'm sure you see the problem here. So I've been thinking for the past few months as to what kind of business I could get into that would be so flexible to work with my overly-random USPS schedule. I'm a photography enthusiast and tried to do something in that area, however scheduling weddings, or any photo shoot really, 3 weeks - 2 months in advance is nearly impossible since I don't know my USPS schedule until a week before, and I have little say over when I work and when I don't. I've looked at what seems to be hundreds of "Work from Home!" programs... no comment on that. Now that leaves me where I am right now, stumped. So I've come here to see if anyone has some innovative ideas about what type of business can sporadically fill in the cracks of my schedule. Thanks in advance!