Other people: Humans will give you money for information tools that make them interact better with other humans. We want to chat with each other, send email, send documents, publish stuff, find things made by other people on the earth, and so on. The vast success of Google, Skype, Ebay, and the various blog sites is of this form. Also, the dominant position of Windows and Microsoft Office is due to their value as an inter-personal communication tool, more so than their value in other respects. Computer games are rapidly shifting their value into this area as well. I would guess it's "The Future" if you are starting a computer business or betting on one.
Media: People will pay for the ability to interact with content through computers, because the computer's digital media capabilities are preferable to the old analog ways of interacting with the same content. For example people prefer to make documents using computers than using pencils because it's easier and the documents look more crisp. We prefer to play games on computers than using plastic and paper props because with computers the shapes move faster and we have to rely less on imagination. It's mainly the computer's digital media capability that we're interested in here, including the physical reproduction of images and sound, rather than its ability for symbolic computation. Music and film are quickly joining this camp, and modern operating systems have a large media element.
Accounting: We are resigned to using computers to mediate those situations where things need to be precisely counted, exchanged, calculated, estimated, or otherwise controlled, and that in the end of the day means counting money. So we will pay for computer applications that count money in the form of airline reservations, taxes, business automation, and any sort of official bean counting imaginable. We like using computers for this because it's slightly less painful than doing the same book keeping by hand. The computer industry was founded here, and a huge part of it is still here. It's now the boring end of the industry, but it's certainly still big. If you're looking for just any job in computers, you're most likely to get one here, especially if you don't live in the US.
Efficiency: Using the computer to improve the efficiency of a technical process, such as industrial design, medicine, manufacturing automation, science, or business optimisation. People will give you money for this in the hope that they will make a bigger profit, or a saving, in the process being optimised, and that this will justify the cost of the computer product involved. In some cases the computer makes a previously impossible process practical. This the kind of application that people imagine computers being useful for in the abstract, but actually the fraction of the actual compter industry that this represents, when one excludes improvements to the computers themselves, is very small. It's a very fulfilling and brain-friendly part of the industry to be in, and so it tends to be over-subscribed with brains.
Computers: Somewhat surprisingly, we seem willing to spend money on computer stuff to make other computer stuff work better. So we buy various software that will allegedly enhance the usability or the security of our computers, as well as hardware devices for this purpose. Fancy mice, carrying cases, virus scanners, firewalls, and screen savers are obvious examples. Less obvious examples are the vast range of goods that computer professionals make to enable other computer professionals to create better computers or software, such as software development tools, programming languages, software libraries, chip design tools, and so on. Although this is often the most technically interesting part of the computer industry to work on, it's also entirely useless to the greater society, as it represents an investment the computer industry is making in itself. Operating systems such as Linux or Windows NT would fit here, but modern systems such as OSX and Vista include more media and communication value than the value of making the computer work.