The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.By Hilary Kramer, InvestorPlace.com NEW YORK ( InvestorPlace) -- Since the financial crisis, the IPO market has been a yawn. But as the equities markets improved over the last six months, investors have been warming-up to public offerings. In some cases, the returns have been stunning. Just last week, the car-sharing service, Zipcar ( ZIP), saw its shares spike 56% on its first-day of trading. Some other hot ones include Qihoo 360 Technology ( QIHU), Dangdang ( DANG) and Youku ( YOKU). All have posted 100%+ returns.