Like footer ads, slide in ads, popup ads, sidebar ads.
Sure there are some places that get more opt ins than others, but if you are not capturing leads at every nook and cranny of your website or blog, then you are essentially leaving hundreds or even thousands of leads just laying around for someone else to grab.
And that means there is a lot of money you missed out on as well.
By giving your visitors the opportunity to opt in in multiple different places on your blog, you will maximize your lead flow and your revenue.
This is exactly what WP Subscribers will allow you to do.