Social networks that allow you to send only the message "Yo" to your contacts. Food-delivery services valued at $400 million. Startups that deliver rolls of quarters to your home (just $27 for $20 in change!).

It isn't hard, looking at a lineup like this, to conclude that Silicon Valley has jumped the shark. The entire Bay Area appears to have given up on solving anything but its own problems: those afflicting the same 20-somethings who are building these startups.

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