I know, I know... I simply can't find how to put the battery meter back by the clock, and some how it seems to have gone... I have OS 10.4.2, I am sure its an easy fix, but I don't know how
In System Preferences, head to the Energy Saver section and select the Options pane. From here, you can check the Show Battery Status In Menu Bar option.
You might think about a menu bar replacement. I use SlimBatteryMonitor. It allows customized power level warnings, you can change the icon shown, how verbose the menubar is and you can change the color of the icon and the power level it shows, if you wish.