Bret, I like your idea of starting with something mundane and optimizing it. Perhaps the first place to start would be to identify potential businesses that are (1) high margin and/or (2) generally inefficient. Then we could use our substantial brains and diminishing (but still respectable) physical energy to beat competitors. Residential contracting (including roofing) is one potential area. Here are a couple more off the top of my head: wedding supplies and services, and funeral supplies and services. Neither one of those two businesses get me very excited, though, unless of course we manage lewd bachelorette parties as well (for either the brides-to-be or the newly widowed). Another possibility in this category is fitness clubs. I've noticed that not many of them seem to go out of business, yet there often seems to be quite a bit of unexploited revenue potential in many of them. For example, why not combine dry cleaning services with a fitness club? One less stop for the consumer to make, and the club already has to have pretty substantial laundry facilities. And another area: services for buying and selling housing. The fees are ridiculously high for very little work by real estate agents and title companies. Can we come up with a new model that would supplant the current Multiple Listing Service one?
Another idea is to find some niche in healthcare since there will have to be some "solutions" that help mitigate the rising costs. One idea I've thought about, but don't have a clue how to make it happen, is to be a middleman between doctors and patients (but not like an HMO). My thinking is that patients want doctors who have experience treating their problems and who are compatible with their preferences (e.g., high touch, high tech, high efficiency/low cost). They also want to know the success rates of doctors for various treatments. And, doctors want patients that match their specialties so they can treat them successfully and efficiently. So, what I'm getting at is a kind of matching service between doctors and patients that improves efficiency and effectiveness. There also seems to be quite a bit of unexploited potential for collaboration between doctors that doesn't now exist. Sure, doctors ask other doctors they know for opinions, but do they access a national or global network of fellow professionals who can give opinions on demand? Finally, I think the benefits of personal biological knowledge will eventually outweight privacy concerns. Linking physical data from millions of patients and performing statistical analysis already may be happening to some degree, but I don't think we're anywhere close to what it could be. Is there a piece of that action we could get? Anyway, I doubt that I've identified anything viable, but maybe this will give someone else an interesting idea.
Finally, there are always strip clubs. The high end ones seem to do a pretty steady business. Plus, we could get in for free!