This is something I’ve been wanting ever since I first got a digital camera. There is now open source “firmware” for Canon digital cameras that will instantly provide an actual battery meter! I don’t know how many times I’ve been using my camera (Canon SD630), knowing that the battery must be running low but having no idea how close to empty it was until the dreaded, blinking red battery icon shows up.
This is but one of many additions available with this method that is akin to, but not actually, a firmware update. Actually, you just put a couple files on your SD card and it takes care of the rest, all with no risk of damaging your camera! If it isn’t what you want, you just take out the card and the camera boots normally. It truly is a revelation. I haven’t tried it myself yet, but I can’t wait to get home to the camera to give it a shot!