Even for desert standards, Bir Tawil is desolate, and it has no decent natural resources, so literally noone wants it.
If you love food and try to be a better cook, here's some good material. Too bad some ingredients, like chilies are a bit tough to find in Germany...
this is safe, but it paints you into a corner over time, where you become paralyzed and can't improve anything. Needs better testing, so changes are safe.
Compared to classifieds in general, it can be much simpler to use, because money isn't changing hands.
An idea, to take or leave: a very active niche for this kind of thing is parents of young children. Very young kids (babies/toddlers) in particular churn through a lot of "stuff" by growing out of it before it wears out. Parents are very active on a range of Facebook groups trading this stuff (though not usually for free, just cheap). In fact the groups are so active that I know people using them daily, and the biggest issue with offloading stuff is posting are lost in the noise. If you're looking for a nice to focus on this is a strong one.
Add $x to each unit of carbon and put it in a fund that the federal government has no access to. Then, at the end of each year, empty the fund completely by sending checks to each citizen.
Unfortunately thanks to incompetence in how this plan was sold by the previous government and an aggressive campaign against it by the opposition, that government lost the following election and now we have the worst of all worlds: carbon tax repealed (the only country going backwards in this regard AFAIK), compensation retained (the incoming government being too spineless to scrap it, despite themselves declaring a budget emergency) and a new braindead "direct action" policy where we now give tax dollars to polluters to encourage them to tone it down (stupidly inefficient and another hit to the budget).
Again: once your kid turns 5 (4, if you're rich and you send your kid to private all-day preschool), you're generally sending them somewhere where one adult will watch as many as 30 kids concurrently, all the while educating them to the point where they can creditably pass standardized tests. That's a harder job than just making sure kids are happy and engaged, and yet we pay far less for it than we do for child care.
Child care is a huge part of why people get crappier jobs than they might. You can't go back to school if you have no savings and need to pay at least $15/hr for child care; in fact, you can't even speculatively take a lower-paying job for career advancement if that job doesn't pay enough to offset child care.
Here in Australia child care is also very expensive, and I agree this is a problem for disadvantaged families (there is some means-tested subsidisation but it only helps to a degree). However: the government has recently lowered the required educator:child ratios, despite the extra cost, because research shows it is important for education (and health, not just when young but into later life). More than this: the research suggests these improvements are most significant for disadvantaged kids.
For more info start here: http://archive.acecqa.gov.au/research-and-publications/.
Clearly the numbers should be adjusted if someone wants to turn this into a serious tax proposal, but it seems possible to design a progressive sales tax.
Yachts were more expensive and due to highly elastic demand, the industry plummeted. Companies went under or laid off thousands.
But don't worry. Guess who works at yacht manufacturing plants? Not rich people. They weren't hurt, and they were fine with taking their money elsewhere.