I'm a growth-stock investor, and IPOs used to be my lifeblood. A steady pipeline of promising companies poised to jump into the market offers compelling ground-floor opportunities, assuming the valuations are reasonable.

Sadly, today's IPO market is rapidly collecting cobewebs. Instead of cheering on the market debuts of hot Internet companies such as Facebook or Twitter, I find myself struggling to stay awake. There's no way to tell how popular an IPO would be for much-visited sites like these two-- or LinkedIn, or perhaps Digg -- but the silence is deafening.

Infant-formula giant Mead-Johnson (NYSE:MJN) went public last month, ending a three-month drought of new domestic stock offerings. Before that, the last IPO took place all the way back in November: online educator Grand Canyon Education (NASDAQ:LOPE).

Neither has been a dud. Priced at $24 and $12 per share in their respective debuts, Mead-Johnson and Grand Canyon Education both trade higher today.

Look back a few years, at more prolific dot-com IPOs such as Google (NASDAQ:GOOG) in 2004 and Baidu.com (NASDAQ:BIDU) in 2005, and you'll find them also trading for several times more than their original IPO prices now.

So what's holding Facebook back? And now that Twitter is gaining popularity in newsrooms, will it risk losing the buzz and settling for less?

Facebook's valuation has been a popular topic since the company turned down Yahoo!'s (NASDAQ:YHOO) buyout overtures two years ago, reportedly snubbing a price tag in the $1 billion range. Microsoft's (NASDAQ:MSFT) move to fork over $240 million for a 1.6% stake in Facebook prompted some to reason that Facebook is a $15 billion company. But Microsoft's investment was really a cover charge in exchange for ad-serving rights on the fast-growing social networking site. Facebook's true valuation is likely somewhere in the middle. It has grown in popularity since then, but tech valuations have plunged.

Facebook and Twitter have had no problem squaring away venture capital money, so it's not as if there's a dire need for either company to go public. However, I will argue that a moribund market for growth stocks needs an IPO like Facebook, Twitter, or China's Taobao to breathe new life into the system.

Cynics would argue that the companies should wait until the climate improves, but what if their IPOs are the catalysts the market is waiting for? As in the good old days, the companies can always come back with secondary offerings at higher prices if sentiment improves.

So what are you waiting for? Update your status to "… is going public," Facebook. Twitter, it's trick or tweet time. The market needs you.

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