Involving customers in your products

I came across adagio tea’s sub-website http://www.teachef.com today and thought it was an interesting way to get customers involved in their product (and it’s also another way to create links to their site across the web.) They send qualifying applicants a sample of that month’s tea for people to create food recipes with (I wonder if I will qualify.) They’re building a small community of avid loyal customers.

If you have a product based business:
What else can your product do (that isn’t it’s typical use)?
How can you get clients involved and active with your product?
What incentive can you give people to participate (samples, prizes, rewards)?

If you’re interested in food, my favorite food blogs are: http://www.slashfood.com and http://www.toomanychefs.com