Muggles' Guide to Harry Potter/Magic/Remembrall

Overview
A Remembrall is a glass sphere filled with white smoke. If you hold the ball in your hand, the smoke will turn red to indicate you have forgotten something. The name is apparently a portmanteau of "remember", "all", and "ball".

Extended Description
Neville is sent a Remembrall by his grandmother in his second week at Hogwarts, and it immediately turns red when he holds it, to tell him that he has forgotten something. However, it cannot tell him what he has forgotten.

Analysis
As written, the Remembrall, while neat, is not particularly useful; everyone has always forgotten something, so the Remembrall would always indicate that something had been forgotten. Perhaps the shade of red would indicate how important the forgotten item is?

The main purpose of the Remembrall is to give Draco Malfoy something that he can steal, to show off his character, and to make it necessary for Harry to fly to recover it. Forcing Harry onto a broom, in a situation where he can show off his natural talent unfettered by organized lessons, is necessary to allow us to share Harry's joy at finding something he is good at in the Wizarding world.

After the byplay on the brooms, Neville's Remembrall plays no further significant part on the story, and no others are mentioned.

Questions

 * 1) How could a Remembrall be made more useful?