title: How to add a delay in async.js iterator (Node)
body: <p>I'm writing a crawler in Node and just discovered the fantastic <a href="https://github.com/caolan/async" rel="nofollow">async.js</a> library. I'd like to not overwhelm the servers I crawl. So I want to introduce a delay between iterations. What is the best way to do this? Can I just call callback() from the iterator inside a setTimeout?</p>