There are many others as well. One of the best resources for this that I've come across is The Publishers Exchange Center. So you've found lists similar to your own. To start with, subscribe to 15 or 20 of them. In most cases, the subscription process is complete in a day or two.
Some lists even offer a sample of their content - if they do, ask for it.
When you have received sample content from these lists, skim through it. And find out the name and contact email address of the list owner or moderator. This will help in tailoring your Joint Venture offer to each specific publication, and ensure a higher positive response from list owners. All Rights Reserved Worldwide.