Help Requested

Quick Question for my Fellow Publishers:
I have seen many authors and or publishers have a sign-up page to get updates sent via email when a new eBook is released. I was wondering if any of you have such a system in place, and if so, how did you set it up?
Right now, I publish the release of new Kindle books on our various TG community sites, but I know that a HUGE advance get our books directly from Amazon, essentially by " stumbling" on them. I was hoping to add a "sign-up" list to announce new Kindle ( and hopefully other formats soon ) releases.
Can anyone help me?
Thanks in Advance!
Sapphire