The Internet, the real estate market, fuel cell technology, nanotechnology and, now, "clean tech" have all experienced an investing "bubble." In retrospect, it is easy to point to signs that the market was inflating to dangerous levels. It is even easier to suggest that such bubbles are a bad thing — precisely because so many investors got burned and lost a great a deal of money.

Bob Metcalfe, an early and successful Internet entrepreneur, see bubbles differently. He sees bubbles as a good thing. Here's his quote: "From Internet history, we know that bubbles are normal. Bubbles are an accelerator of technology progress. Bubbles go against the status quo. We should encourage bubbles."

I suspect that such statements are much easier to make when you're already a billionaire; as opposed, say, to someone to just lost a large amount of money in the stock market. Nevertheless, there is a certain logic to his argument and we may want not to dismiss all bubbles as cases of irrational investors getting sucked up by the winds of "irrational exuberance." Instead we want to view them as "technology accelerators." (This might not ease the financial pain of those who lost money in the bubble, but it might at least make them feel a little bit better about themselves.)