Wally, a wallpaper app for Android that pulls from Wallbase.cc, popped up on Google Play at the end of last week as a great example of a developer putting Material Design to use. The app utilizes rippling touch animations, transitions that fade behind layers, floating buttons, and page swipes that colorfully slide from section to section.
Oh, it also has a solid wallpaper collection, with Muzei support, for those looking to spruce up their home screens. You can browse and save/set wallpapers, filter through a variety of options, and even search by text and color.
The app is free.