I also use pocket plus, it's a nice program. if you have Wisbar Advance, it also shows the battery and memory in the top right corner of the start bar. it's overkill in my case because I use both and I have 2 battery meters. the Wisbar meter is a little small tho.
Battery Pack is another one I've used, it also shows the battery meter in the start bar. its similar to pocket plus, but I thought it too much space on the today screen.