Some investors seem to have forgotten the outcome of the first dot-com bubble with so much money flowing into Silicon Valley start-ups these days, according to The New York Times.

While similar to the first bubble, many of the companies are yet to find a clear path of monetization, and ad dollars have become a proven method for revenue. The recent wave of acquisitions has fueled fears of a second bubble.

In October of 2006, Yahoo made a hefty investment in Right Media, only to purchase the company outright six months later for quadruple the price. This left Brian O'Kelley, CTO, Right Media, literally giggling all the way to the bank.

“There is no way we quadrupled the value of the company in six months,” says a candid O'Kelley.

But not all is bad. In a recent iMedia article, Tom Hespos leaned heavily on the power of advertising to fuel the internet. The web, argues Hespos, is not only good for attracting a large crowd, but can deliver "laser-like targeting" to let advertisers know who, exactly, is watching. This means a higher return for advertisers, which means more revenue for the web.

It's hard not to shudder, though, when companies like eBay admit they overpaid for companies like Skype by the billions of dollars.