SquidMelon

Screen Utility

Free

Comprehensive Overview of Screen Utility for Mac

Live Wallpaper

Paid

Dynamic Visuals with Live Wallpaper for Mac

Head for Facebook

Paid

Floating icon that gives you quick access to Facebook.

Head for Instagram

Paid

Floating icon that gives you quick access to Instagram.

Lock Screen Plus

Paid

Customizable Lock Screen Enhancements for Mac