Besides the Android ICS GUI Design Kit that can be used in Adobe Photoshop, I also think (and love!) that sketching is a big part of UI/UX designing, while it can be messy, but it definitely help in quick idea visualization and aid in brainstorming.
So here I come up with two sketch templates for Android App, using the Samsung Nexus S and Samsung Galaxy Nexus as the sample devices, and put them on an A4-sized PDF with almost real-life size so designers can sketch the app with the size as close as the real device (don’t blame me if there is one or two pixels off! /jk/).
Android app designer, go create some awesome apps with the GUI Design Kit and GUI Sketching Kit!Android UI/UX