Shares of Coupons.com gained 88% in their first day of trading Friday, as the investor shopping spree for IPOs continues. The company, which provides digital coupons for consumers, saw its shares jump $14 to close at $30 apiece, a strong showing especially considering the IPO price range had already been raised. The company sold shares to initial investors at $16 each, up from the $12 to $14 a share range expected when the company filed its plans to go public last October.