Erratic volume is a basic annoyance of television viewing. From commercials increasing in volume to loud scenes in movies, there are times when you need to dive for the volume control. There are several strategies of automatically reducing volume for sudden increases, however, I think most people would rather be able to control it themselves - if they could easily get back to the previously determined comfortable volume.
I propose adding buttons and a set of remote control codes to remotes to allow the current volume to be noted and halved and restored at the push of a button. The analog nature of increasing and decreasing volume means that the volume does not decrease quickly and is also, unless it had a number which you noted, sometimes difficult to get back to the volume that you had determined was the optimal listening volume.
In the attached drawing I just added a simple illustration of a version with 1/2-, M, and 1/2+ buttons. Pressing the 1/2- button would decrease the current volume by 1/2 of the volume range beneath it and pressing it again would return the user to the previously comfortable button. M is Mute and pressing teh 1/2+ button would increase the volume by 1/2 of the range above which would prevent it from going to close to maximum volume at once - unless you were already listening at that volume.
Simple, fairly easy to add to any number of remotes, and would increase the viewing pleasure of regular tv or movie viewers and also for people listening to music or playing computer games.