Hustle is an email opt-in plugin that is full of features. It can create email opt-ins, custom ad pop-ups, slide-ins, and even floating social bars. The best feature of WPMU Hustle is that it can even bypass Adblockers without any problem, which means you can show what you need to show your visitors and customers.
This is the EXACT same plugin as distributed by the developer on WPMU DEV. The developers’ links are provided above.