The 2008 European Championship in Football will be co-hosted by Austria and Switzerland. The Swiss government commissioned a study on the economic impact, which concluded:
Between 2.8 and 5.4 million visitors are expected to view matches, either at the stadiums or at the public viewing areas, helping to generate up to 1.11 million overnight stays.
The study estimates that Euro 2008 will provide employment equivalent to up to 7,350 full-time jobs, although the majority of extra work generated will be a result of overtime rather than through the creation of new jobs.
In other words, Euro 2008 will be a bonanza for bartenders and hotel-workers.
Update: Here's the Reuter's article quoted above. This AFP story emphasizes the additional boost from people who can't afford to buy tickets (i.e. people attracted to city centers for the party atmosphere surrounding the big screen telecasts), but doesn't say anything about the differential spending patterns of the ticket buying vs. freeloading types. The AFP story does note that most of the impact "will come from spending on accommodation, food [and] drink." Which brings to mind the benefits and costs of selling beer to the fans from Engerland.