What I use isn't free (there is a free version though), Battery Monitor, shows a big clear % in the status bar rather than small numbers on a white battery icon or inside an outlined battery icon, which aren't as easy to see. I had Battery Alarm on my older phone, it beeps when it reaches a set % (like 20% battery).
I'm not sure if it's app specific, as I've seen the same app give 1% increments on many phones but only 10% increments on Motorola phones (my old Motorola Quench and Charm would only work on 10% increments).