What effect has the Internet had on the world economy?

It's worth researching the concept "crisis of value" in the p2p foundation wiki and blog search boxes. There is a remarkable book on the topic: The End of the Market. The rise of the service economy and the death of the market-clearing price Edmund O'Sullivan has summarized its theses: "*The emergence of the market-clearing price as the central factor in economic affairs was followed by a steady decline in the contribution tangible good production made to economic output. By the end of the first decade of the 21st century, more than 80 per cent of GDP in many advanced economies was accounted for by services (intangibles-- Chapter 1). The economics of intangible production and consumption invalidates the role of price in stimulating production, consumption, saving and investment in service industries (Chapter 2) Value in intangible production is created through interactive relationships at the individual level among participants in service markets (Chapter 2). Technology has led to the separation of the process -- the tangibles and mechanisms that support value-creation – from the relationship at the individual level where value is actually created in services (Chapter 2). In intangibles, markets and industries necessary for the production and consumption of tangibles are being replaced by intuitively-defined communities within which individuals interact to create value (Chapter 3). Companies producing intangibles will face a growing calculation problem because of the decline of the validity of price as a stimulant of service production and consumption (Chapter 4). Companies producing services with horizontal structures, minimal centralised decision-making and no external financial liabilities will have a competitive advantage compared with competitors that do not (Chapter 4). The separation of process from relationship in value-creation in service industries will encourage companies to focus on one of the two critical skills in service value creation (Chapter 4). Governments will face increasing challenges in creating value in the service markets they participate in and should concentrate on the process elements of service value-creation (Chapter 5). The rise of service industries raises questions about ideas of social and economic progress that have been dominant for two centuries (Chapter 6)" (http://theeconomicrealms.blogspot.co.uk/2012/12/the-end-of-market.html)

If your measures of health/value are GDP and the Dow, the Internet is the Great Destroyer of Value. If your measures are happiness, local responsibility, sense of community and other such alternatives, the Net is the Great Manifester of Value. That, plus everything you said, Seb.

By freeing up resources that supported unnecessary physical proximity and middle man functions, the net expanded the pool of necessary but insufficient ingredients for innovation.  Because imagination and leadership to make the best use of these "new" resources have not always been available, the results have not always surpassed the value of what they replaced.

Arguably the Internet became an accelerator of existing trends. Whether that's good or bad it depends on the effect of those trends.