There’s something about TV theme songs: Although they aim to be timeless, in retrospect they’re always a relic of their era. Perhaps that’s why they make us so nostalgic. So, when we stumbled upon this great playlist of songs from Seinfeld, featuring the show’s own quirky, bouncy, bubbly intro, it got us thinking about all the other ’90s TV themes we haven’t heard since, well, the ’90s. Over the next few days, we’ll be posting mixtapes of themes from some of that period’s most memorable programming blocks. Today, we’re kicking it off with a compilation of great ’90s Nickelodeon music, which you can listen to after the jump. Oh, and if you’re curious about what ever happened to the casts of these shows, check out our recent update on what they’re doing now.