As of 2012, what were the best "Frighteningly Ambitious Startup Ideas" other than the ones mentioned by Paul Graham?

Dear fellows, I would not call any of suggested examples to be anything scary yet simple because human is required to participate for all of them any of them would be even exist. Neither I did find any of them to be anything close to be `frighteningly ambitious ideas` or understand well how something like match could change the world or be scary ? Perhaps author meant something else with the question like most `cool` new ideas. One of the most scary innovations & start-ups are high-frequency trading algorithms and robo trading. It is very much same as designing a commercial airplane or car having no driver or pilot inside in it, not knowing either where it is driving & flying at all or perhaps better example would be two countries having war between each other with no humans participated for it. For those of you who do know what it is, read the basic´s, 80% of the market turnover & decisions is not made by humans anymore, machines do so. What makes it even more scary is the fact `Rise of Machines` in the financial market fights also between each other in these days, not against of humans itself only. There is robotic money war going on 24H hours per day, 365 days a year, does not eat or sleep. It also read the all news and earnings and macro-economic reports plus make analyse more fast than any human with computers could ever do. If you are not scared yet this is not `tomorrow`, it is situation today.  In electronic trading algorithmic trading or automated trading, also known as algo trading, black-box trading or robo trading, is the use of electronic platforms for entering trading orders with an algorithm deciding on aspects of the order such as the timing, price, or quantity of the order, or in many cases initiating the order without human intervention   High-frequency trading utilizes lightning fast, powerful computers to execute automated trades on more than one market. Is it fair to everyone else ? Here's what it is and some of the issues surrounding it to provide you with a high frequency trading explanation. The use of computers by investment banks, hedge funds, and other institutional investors has been around for decades and the acceleration they give to transactions and fluctuations on the exchanges gives rise to some interesting scenarios at time. As more powerful computers evolve, so does their use for generating trading profits. One of the latest developments of this is known as high frequency trading. Many investors don't know what it is and need a high frequency trading explanation. Algorithmic trading is widely used by pension funds, mutual funds, and other buy side (investor driven) institutional traders, to divide large trades into several smaller trades in order to manage market impact, and risk. Sell side traders, such as market makers and some hedge funds, provide liquidity to the market, generating and executing orders automatically. A special class of algorithmic trading is "high-frequency trading" (HFT), in which computers make elaborate decisions to initiate orders based on information that is received electronically, before human traders are capable of processing the information they observe. This has resulted in a dramatic change of the market microstructure, particularly in the way liquidity is provided. Algorithmic trading may be used in any investment strategy, including market making, inter-market spreading, arbitrage, or pure speculation. The investment decision and implementation may be augmented at any stage with algorithmic support or may operate completely automatically.

Invisible writing on any surface - so if you are at work or even at home, you can type text on to a document, but it remains invisible and the only way to access the writing is if you enter a password onto the surface/screen. The only way to access this writing is if you move it  to another document and then type in a password to access it. The ramifications of this are if your parents, partner, boss etc. walk past your desk and ask to see what you are doing, they will not be able to see anything and according to them there is nothing there. If they ask you what you are typing, you can just say you quickly switched over to another page. To me, there is something Orwellian about this idea and that is why I chose it as I felt it was very much in line with the impermanence of things that Paul Graham's essay partly refers to. It would function like invisible ink. But instead of using a coloured marker to 'show' the invisible writing, you could only make the writing visible on your screen by typing a lengthy password. And as astutely observed: The important thing is that it doesn't have to be a blank screen. It is that only *you* can see the text you are writing and no one else can. That might be some Random Holographic Imaging device. It might be typing on the new Google Android Goggles coming out. Yes, this would destroy productivity at a lot of work places, but it would be so awesome to see someone pull off a piece of software that could make this work.

Online grocery store. People would love this. Delivery twice or 3 times a day. Subscriptions (deliver milk ever 2-3 days) The key for this is to integrate local grocery stores. Edit: I'm not talking about an online store that sells grocery. What  I mean is an API that is integrated to the inventory of all grocery stores that allows for real time transactions and communication. between stores and buyers

Pipelines to your home which can deliver anything So you want grocery, boom, a cylindrical storage device is on its way from the grocery store (or the nearest walmartesque warehouse). You want ice cubes, a frozen cylinder is on its way.

Completely reinvent the banking industry and reshape the global financial system in the wake of it.

Match up qualified contractors and investors with the owners of buildings that need short-payback energy efficiency projects.  When a contractor would otherwise be  idle, he or she could be doing an investor-financed project that would pay back the investor out of the building owner's energy savings.

I dub this idea Cloud Currency - Instead of dollars and cents, people pay for products and services on the web with actual megabytes / gigabytes / terabytes / petabytes (?) of data storage space. As 3D printing / nanolathe (http://en.wikipedia.org/wiki/Nanolathe) technology develops, people can use this Cloud Currency to pay for actual physical objects. Somehow.

Affordable telepresence that just works, perhaps co-opting a device that most people would own for much else besides. In spite of  everything about the rapidly shrinking world, when it really matters people fly. And nothing really significant happens until you meet. The subtle non-verbal cues matter. It is nearly impossible to build relationships or trust over currently available mass market videoconferencing technology. Widely available telepresence would actually eliminate distance.

Software that programs itself and understands the requirements by itself would be great. Programming is glueing together a ton of APIs, the business logic/algorithm itself in the most cases is only representing a tiny portion of the source code. Having that would change everything, because a lot of problems would be solvable with short notice. Software sits at the heart of all relevant processes. This idea is not new, I think one of the first how had this idea was von Neumann in the 1950ties. This singularity is coming closer, but there is probably a lot to do to achieve it.