The effect that the Times Forum (formerly known as the Ice Palace) has had on downtown is enormous. Obviously, the Lightning are a big part of that. However, you also have to look at the concerts, the TB Storm games, collegiate tournaments, exhibitions and other special events (like religious programs, inspirational speakers) that draw hundreds of thousands of people into the district.
The direct economic impact is huge, considering the money spent at restaurants, bars and hotels, parking revenues, trolley rides, etc. But the indirect impact, i.e. how the Forum has acted as a catalyst for other types of development along the water in this area, is immeasurable.