Most Web users made more online purchases this year than last, according to a new study by Allurent, a Cambridge, Mass.-based company that provides services to e-commerce retailers. The study, based on a survey of 638 U.S. adults, found that 53% spent more this holiday season than in 2005. In addition, the majority of respondents--52%--said they spent between $101 and $500 online during the last holiday season. Two-thirds of respondents said they intend to spend even more online next year. When respondents were asked what factors kept them from making more online purchases this year, the top answers included high shipping charges (cited by 42%), that shopping in brick-and-mortar stores is easier (24%), and product outages online (21%).