I've ended up finding a lot of sites that have video game sheet music or guitar tabs on them, and thought I'd list them here1:
- NobuoUematsu.com - Sheet music (in gif format) of music by (you guessed it), Nobuo Uematsu
- Nintendo on Piano - Sheet music (in PDF format) for Castlevania, Metroid, Super Mario Brothers, and others
- RabiteMan's Game Music - Sheet music (in .gif format) for Final Fantasy IV and VI, Chrono Trigger, and others.
- Video Game Sheet Music - Sheet music (in pdf or NWC format) for Megaman, Super Mario Brothers, and others.
- Game music themes.com - Sheet music (in pdf format) for many games, sorted by console type.
- Shivasar’s RPG Sheet Music - Sheet music (typically in .gif format) for a number of RPGs, including lots for Chrono Trigger and many of the Final Fantasy series.
- Riulyn's RPG Sheet Music Shrine - Sheet music (typically in .pdf format) for lots of RPGs, including Chrono Cross, lots of Final Fantasy's, and others.
- NinSheetMusic - Sheet music (in .MUS format) from various Nintendo games, including the Mario Brothers games, Metroid, Pokemon, Castlevania, and others.
- Ichigo's Sheet Music - Sheet music (in a variety of formats, including PDF, gif, and MUS) for a whole bunch of games (titles list here)
- Piano Themes - Sheet music (in PDF format) for a huge list of games
- Video Game Jam - Guitar tabs (as .txt files) for a lot of games, sorted by console type.
- Nintendo Tabs - Guitar tabs (as .txt files) for a number of Nintendo games, again sorted by console.
It's nice to have something to distract me from the mountains of papers that are awaiting grading.
1 (VGmusic.com's list of links helped quite a lot)