Dockem universal wall mount
The Dockem ($15) is essentially a "miniature shelf" for your smartphone or tablet. It attaches to the wall using Command strips, those thick double-sided adhesive strips that are supposed to come off without damaging your wall.
The Dockem works with any device that is less than 20mm thick, including case. The dock is made up of two sides, a left and a right -- you measure out where you want to put them depending on the width of your device.
A potential downside is that the Command strips lose adhesiveness after multiple uses, so if plan to move it a lot, you'll want to load up on extra strips. On the other hand, you're not putting any holes in your walls.