Online deal forums are public places where participants share with each other news and information regarding "deals" such as sales promotion events by online stores. The large number of messages in the forums and their inherent uncertainty make it difficult for even seasoned users to identify useful deal information from the forums. We develop an intelligent deal alert service which assists ordinary Web surfers to find useful deals by mining online deal forums. It periodically crawls relevant deal forums to collect fresh message posts and responses, and evaluate them using a form of probabilistic text classification. Users may be notified of new, "potentially" useful deal messages via emails or they may browse them using their favorite Web browser. We train and evaluate the service using deal posts and responses collected from actual deal forums in the Web. The preliminary evaluation results show that the service is quite effective in reducing the time to find useful deals.