iPhone cases are pretty damn boring, they're like a wasteland of silicone and plastic sameness. Not this one! This case is awesome. The SmallWorks BrickCase ditches those tired materials for Lego, turning your iPhone 4 into a playground for Lego bricks.
It's only $20 on Amazon and works great with any Lego bricks. Go wild, the whole back and top of the iPhone is open for your creative interpretation. This is one of the few times where I approve of adding bulk to your phone.