I don't know about you but I hate plastic battery covers. More often than not they end up as creaky annoyances. The problem is, it's only usually "dumbphones" that get encased in nice shiny metal. The Sony Xperia X1, however, is an exception to the rule. Using little more than a bit of "spit and polish", Xperia user Paul White gave the metal battery cover on his X1 a gorgeous chrome effect to rival even that of the incredibly overrated iPhone. Full write up on his blog.
Sony Xperia X1i hand polished chrome battery cover