If you're on the cutting edge of Windows Phone hacking and homebrew then you probably have a fully unlocked device with a custom ROM running "Tango" 8773. If so, then you may want to take a look at this latest creation from Zealson over at XDA.
The simple XAP file will launch a mini-app to allow you to change the battery meter to a custom version. The meters have four options available: default, horizontal, vertical and circular with the latter three having a percentage number for a semi-accurate reading of your remaining battery life.
We say semi-accurate as the percentage doesn't get down to the 1% range and instead looks to be at 10% increments. Such a limitation is due to the API though who knows what magic these devs can whip up, so there may be hope for 1% changes too.
Of course as we mentioned at the beginning, only fully-unlocked ROMs can install this and luckily the Titan and Radar are now in that camp too.
Source: XDA Forums