Considering the many many many Sonic the Hedgehog games pumped out by Sega over the years it shouldn't come as a surprise that the series includes quite a lot of solid music.  From his Sega Genesis debut through the dark days of the Sega Saturn onto a Sega Dreamcast rebirth and beyond into appearing on non-Sega consoles, Sonic and friends have racked up plenty of quality tunes.  NeoGAF forumite Sciz has spent a lot of time and effort to create "Cool, Sweet, & Catchy!", a Sonic the Hedgehog music appreciation thread that includes a little history for each game's soundtrack (yes, even the less-than-stellar games such as Sonic Drift and Sonic Shuffle) and links to samples of the best of the mighty music.

Between 1991 and 2008, Sonic the Hedgehog has managed to reach some of the highest heights in gaming as well as some of the lowest lows. His games simultaneously rank among the best and worst in platformer history. But in spite of the varying quality of the gameplay, the series has a single constant: fantastic music. Over the last seventeen years the series has hit J-pop, Europop, rock, metal, jazz, electronica, rap, funk, and many other genres, and pulled (almost) every one of them off superbly. This thread is in honor of the dozens of different men and women who have worked behind the scenes to make that possible.

While reading the article I was surprised at how much of the more recent Sonic songs I could not recall.  Music from the original Genesis games bounce around inside my brain all the time, but I couldn't tell you what the music from modern titles like Sonic Rush Adventure sounds like (and I've spent more time with the latter than the former lately).  A game or two appear to be missing from the list (regarding Sonic Labyrinth, Sciz says "Labyrinth is one of those that I couldn't find the music for, and I don't honestly care enough about it to spend too much time looking.") and one of my favorite Sonic songs, the theme from Bullet Station found in Sonic Heroes, has been excluded (blasphemy!), but on the whole you're bound to lose an hour or two exploring all of the great tunes.