"Burrito Bowls" took investors by storm in 2006. Investors are still chomping at the bit for shares of Chipotle Mexican Grill ( CMG), which have more than doubled since the Mexican restaurant chain's IPO last January. The Chipotle initial public offering, which raised $199.3 million for the Denver-based company, marked a strong beginning to what proved to be a solid year for new stock offerings. The year ended on a high note, after suffering through a bit of an IPO drought during the summer months. In all, 250 companies went public in the U.S. in 2006, raising $49.8 billion, Dealogic says. That's a 23% gain over 2005 and the second-best year for the IPO market since the height of the dot-com boom in 2000. But the domestic IPO market still faces an uncertain future in 2007, as an increasing number of foreign companies are deciding not to list their shares on either the New York Stock Exchange ( NYX) or Nasdaq Stock Market ( NDAQ). Rather, many European companies are choosing to list on overseas exchanges, which are not bound by strict U.S. regulatory mandates. One thing that could fuel the IPO market in 2007 is the red-hot private equity business, which has taken a record number of companies private over the past two years. In the coming months, some of the buyout firms may look to cash in their chips by throwing their debt-laden acquisitions back into the marketplace.