Power Sneakers
From Sonic Retro
Speed Shoes are power-up items found in monitors in most Sonic games. They cause the player to accelerate much faster than normal. The players top speed is also increased in some games. When they are collected the music usually speeds up or a new music track will play; the latter occurs more often when the game uses waveform audio (such as Sonic CD or the modern games) or is on a system lacks the power to speed up the music to that level in addition to the other game processing tasks (such as some of the game gear Sonic games).
External Links
The Most Useless Power-ups in Videogames - A 1up feature which mentions the speed shoes.