Lightbox popover plugin for generic popups

I am looking for a nice pop-over plugin for my wordpress site.

I want it to pop up in a lightbox style popup that dims out the site behind it, that automatically centers, etc.

WordPress popup domination looks like it has everything I need, except from the descriptions it looks like it pre-makes the plugin for email lists. I’m wanting to pop up ads, not email lists. Is this possible with that plugin? If not, what plugin is a good alternative? I tried the wpmu popover plugin but it doesn’t dim out the background and it displays on a fixed section of the page (meaning it’s not always centered).