For a web company to even want to partner with you, you need to fall under one of these three categories:
1) Create Revenue
Whether you are creating revenue for them or they for you- revenue makes the world go ‘round.
2) Increase User Base
Do you have a user base that a partner can tap into? What will you get in return from exposing them to your users?
3) Improve Product/Offering
Do you have a nifty tool that will make the user experience better for a partner?
Each web company puts each in personal priority. At times they can be focused on either product, growth, revenue, two of three or all three. It really all depends on timing. Try to keep these categories in mind when dealing with partnerships.