avaaz.org, there's a charmingly naïve online petition for the UN to start issuing a "globally recognized world passport". It claims it needs a million signatures and as of this writing, it has a whopping 310 of them. I'm not sure what impact anyone thinks such a petition would have. It's not just that governments would ignore the idea: citizens of most countries wouldn't want that passport if it acted as a real passport and allowed the holder to live and work in the country (in this case, the world) that issued it. Can you imagine how many major country's social services would collapse under the weight of unlimited immigration?
As it turns out, there are plenty of "second passports" schemes out there.
You may be surprised to discover that there is a World Passport. I see it mentioned repeatedly on Web sites and those who are knowledgeable about expat issues know that it's a curio, at best. It's issued by a non-profit organization, not a government, and I've read reports of refugees acquiring them, only to discover that countries don't recognize them. However, they're popular enough that counterfeit World Passports are being sold.
There's also an online market for diplomatic passports. They are, of course, scams and will land you in legal hot water if you're stupid enough to pay for one. Of course, sometimes people get away with this (you really want to read that story!) and the results can be astonishing, but no, don't do this. Particularly don't do this if you're trying to get into any major industrialized nation. Maybe the Central African Republic won't scrutinize your false passport too closely, but otherwise, forget about it.
Or you can read this long list of fake passports compiled by the government of the Isle of Man. It includes passports from the non-existent British West Indies, Zanzibar, which doesn't issue passports as it's part of Tanzania, and my favorite: the Conch Republic.
Or hell, if you just want to get right down to business, you can visit www.falsepassports.cc and buy a passport online for anywhere between €400 to €700 (more if you want a driving license and ID card).
Myself, I'll probably have a French passport in another year or two, but that's because I will be able to legally apply for French citizenship. I would skip the scams, but nonetheless, they're there for you.