The paper "Do Former College Athletes Earn More at Work?" by Daniel Henderson, Alexandre Olbrecht, and Sol Polachek, is a featured article in the Summer 2006 issue of the Journal of Human Resources. The authors find that there are financial benefits associated with athletic participation, but they are not uniform across all athletes. The study is based on a survey of 4200 male college students in 1970-71, of whom 16% were athletes.
Here's a short summary of the findings:
Henderson and his co-authors found that a slightly higher percentage of athletes than non-athletes were in higher income brackets. Most athletes in business, the military and manual labor were better off wage-wise than non-athletes working in those fields, but not all athletes enjoyed a premium from sports participation.
One field where former athletes earn less is education. A disproportionate share end up teaching in high school, perhaps to maintain their interest in athletic competition. Former athletes earn 8% less in this occupation.
I found the following statement from Henderson interesting:
Although college jocks have a reputation of being poor students, we found that on average, former athletes were making more money than non-athletes six years after college. This may be because athletics enhance existing skills during college or because athletes learn skills on the field that they can apply in their careers.
Crank up the NCAA hype machine! But seriously, this is an article worth reading for academics interested in the field.