So I convinced you to add a popup to your site? This is one of the more technical things in the book so I wanted to find an easy way to get one running on your site.
To that end, I recommend SumoMe. It’s a free tool that makes it simple to put popups, slide-ins and other great feature on your website. It’s what I use, and you should too.
FYI: the pricing for 1 site is $47, for 3 is $77, unlimited is $97
Have you looked at SumoMe? The folks at AppSumo have created it; it's a tiny, smart pop-up that's designable in about 5 minutes and plays nicely with Mailchimp, Aweber, and so on. It doesn't offer many design options, but it's great for free.
Tim, one thing that really annoys me about pop-ups asking me to subscribe is when they pop up even when I HAVE subscribed, and I've clicked through from a link in the newsletter! Are any of the pop up systems smart enough to recognise that?