I use Mailchimp for my list. You can see my sign-up form here. The link is on my blog, my website, and at the end of my ebooks. I only email readers when I have a new publication out, but some authors use it to send newsletters to their fans. Seeing your list grow is satisfying - it belongs to you, and is a form of insurance in case something unwelcome happens with a platform you sell on. It's another component of self-publishing you have control over.
Mailchimp is free and provides a fantastic service, but its interface is not totally user-friendly. If you get stuck, Desmond X Torres has written a how-to guide on Kboards, which also mentions an alternative option for Wordpress users. Unable to customize your sign-up form? Kay Bratt has the answer here.