Go Launcher EX has a 'Go Launcher Notification' plugin that enables badges for apps such as Facebook, missed calls and texts, emails through the Gmail app, and Google Voice. unfortunately, it requires that an icon still displays in the notification area and that is always so unnecessarily cluttered. i often turn it off in the launcher preferences somewhere. i now use TSF Shell, a very expensive launcher but far more neat to look at and use than Go, but it only supports app badges with Gmail only. no other app other than missed calls/texts. i have rooted mine and turned off any icons that display in the notification area except vital stuff like battery, signal, wifi status and free RAM (i monitor it as my phone has very little and if it goes over a certain percentage used it crashes). the badges still work without the icons up top in TSF shell.
i think Samsung's Touchwiz launcher that should have come with most Samsung phones, and perhaps HTC's Sense would to, supports some badges, but i forget how i enabled them in Touchwiz, and i haven't used Sense yet.
Rom Toolbox Pro is the app to get if you want a custom battery gauge. it doesn't require flashing a ROM. but as with anything root, i recommend backing up everything first!
"If you treat your system like a kiln, don't be surprised when a brick comes out the other side."