This is very common in the online business world where affiliate, reseller and joint venture arrangements cause companies to grow over 1000% with just one deal.  This is because everyone wins.  Usually there is a revenue share so both businesses make more money and the customer gets high quality products endorsed by businesses they trust.

The biggest mistake you can make when you do one of these deals is to not reduce the business joint venture to a legal document.  These documents do not have to be complex but they serve an important purpose.  First and foremost, they document the business terms- this is important to make sure everyone is on the same page.  Second, they provide legal protections for both sides which is equally important.

One thing that savvy businesses like to sneak in is an exclusivity clause.  These come in many forms but, in essence, their goal is to restrict you from doing similar deals with others.  Now, there is a price for everything and so if you are getting such a unique deal or the other side is making a significant investment in the deal, perhaps one might be worth it.

However, in most cases, it is a trap that will significantly limit the growth of your business and options you may have later.  Let joint ventures thrive on meeting business objectives and not based on legal ties or legal requirements.