Looking for a basic “Subscribe” type of plugin.

I’m just looking for a simple plugin or feature that would allow for a single text box that people can put in their email address and subscribe so they’ll get an email when there’s a blog post in the future.

All the subscribe plugins that I’ve gone through make people register to the blog. I don’t really want people to have to create a login to my blog, it’s not really that kind of site.

Any suggestions? Is there already something built in that I just missed?

Thanks,
Michael