1. The demise of newspapers.
If newspapers evaporate, it will prove to be a disaster for democracies. The web will never provide the same oversight as newspapers. It is an unreliable medium for news dissemination. Like television, over time it will become more of what it is, not less. It will destroy the newspaper industry but it will not replace it.
2. The proliferation of pornography.
The most upsetting and degrading forms of pornography are now just two clicks away from every nine-year-old.
3. The devaluation of intellectual property.
Artists' work used to be among the most highly valued of commodities. This is no longer true. This development has nearly ruined the music industry.
4. The acceleration of dumbing down.
There is a direct correlation between celebrity culture and the dumbing down of society. The web has stimulated celebrity culture to an unprecedented extent.
5. And one more thing I hate: Twitter.
What's the difference between pizza and the internet? Glad you asked. You're allowed to criticise pizza. But as soon as you criticise the internet, you get e-mails and comments from devout web zealots telling you how stupid/backward/clueless you are. They'll be rolling in any minute now ...