Looks like those folks at Windows Phone Hacker, specifically Jaxbot, have been working on some neat ideas for our devices. This latest trick involves making custom Tiles for the Start screen, allowing a theme of sorts to give a more unique look for your phone. Previously, they released the "Folders" option for the Start screen.
The method is not yet available as Windows Phone Hacker is once again feeling out if there is any interest in releasing it--those man hours in creating and refining this don't come out of no where, after all. Personally, we think it's pretty great looking and would be fairly excited to see this happen.
Best part is this doesn't require any deep interop-unlock, just a simple developer unlocked phone (either official or ChevronWP7 Labs), making this a seemingly straightforward hack. If interested, head over to Windows Phone Hacker or hit them up on Twitter @wphonehacker to let them know!