An XDA member, liorry, recently developed a really smart and useful app called Overlays - This application lets you float your widgets anywhere on your homescreen. This app comes in a free version in the Google Play Store and it's absolutely awesome.
App does some really cool things such as floating your music widget so you can check your music while managing other app, also lets you to float a calculator, so you don't have to open a calculator separately while working with other app.
Except your stock/downloaded widgets, app also offers its own widgets, such as battery bar, missed calls count, unread SMS count and more.
The app comes also in a pro version, which offers creating an overlays profiles by apps and more.