Sendy widget pro version can be downloaded from codecanynon
Here is the list of features
-Support Multiple list subscription
-Curl enabled , user never leaves your site
-Subscriber count in Frontend of widget
-Encourages the collection of only information that you actually need i.e. an email address (or name if you want)
-Show number of users already subscribed to list in frontend
The plugin can be downloaded from codecanynon.