Since you already know how to replace the stock battery icon in the HTC EVO's taskbar with one that displays the remaining percentage (tutorial here), now let's talk about some other options.
Thanks to wes342 of the xda-developers forum, we've now got a nice selection of monochromatic and colorful icons to choose from. They all display the percentage, as shown in the image, but some are available without it too.
If your EVO is rooted and running either a deodexed stock ROM or one of several specific custom ROMs (CyanogenMod, myn, and EViO 2 as of today), then you can flash the icon of your choice; all of them can be found as separate downloads at the xda-developers link below. As always, do a Nandroid before flashing anything so you have something to return to if anything undesirable occurs.
I tried to flash the multicolor smooth circle icon but when I rebooted, my old "stock battery with percentage" icon was still there. I didn't see any errors while flashing, but it obviously didn't work on my EVO, even though it's running a deodexed stock ROM (SteelROM RevH). Did you have better luck with any of the icons on yours?[xda-developers]