Filler added that those in the photovoltaic field hope to see solar conversional devices in everything we own, including roof shingles, sign posts, clothing, etc.

FORBES: iPhone 2.0: Solar-Powered Mobility

Marketers buy the ads and then figure out their return on investment based on how many people click on them, "like" them (remember the value of a "like") or take some other action (sign up for a contest, download, etc.).

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But to be fair to both sides, I also question the wisdom of the idea that the current pullback in stocks is a sign that market players are concerned about the economy (or Greece, China, etc.).

FORBES: Confessions of a Market Environmentalist