Link them to a variety of Sports magazine subscriptions...golf, tennis, football, basketball...you name it. Acclaim Subscriptions has them all and pays great commissions on sales in the US, Canada and Worldwide.
There are a ton of sports affiliate programs, it's all about matching a program with your target audience.
Depends on your site and what the specific niche is. I use to work for Bodog, and they had a really awesome affiliate program and it works with just about any sports website. But it's sportsbetting, which may or may not work well with your site. If you are doing football, College Jersey seems to be doing well, and they have some really good email newsletters going out to their affiliates, but they sell college football jerseys of rising stars, which again may or may not suit your website. It really comes down to your specific site.