In animation float, there is a curve you click on. there are presets but none that start at 1 and go down to 0. This could be used to fade music down. Also, why can't you type in the values? I'd like a input to type in start amount, end amount and time. That way, you can say 1, 0, 3 (for volume 1 start, volume 0 end, 3 seconds to do it.)