I've never given a rundown of all the projects I've got rolling around, so here we go! First up is Jet Set Radio for Sega Dreamcast. All game data is stored in CRI's AFS format. The most common use I've seen for AFS is for storing music, but the container can hold any file type. Textures are Dreamcast specific PVR format, viewable with IrfanView. Details of other formats are as of now unknown.
Also of note is Bionic Commando: Rearmed, lots of wild data in there. The game runs on compiled Lua code and keeps all its data stored in a huge file store. Individual pieces of data are stored in XBox formats that I haven't investigated much. The music is available as OGG.
I did some work on Bust a Move 2(the dancing game) also. The meshes look like they store a lot of animation data and the verts are hard to make out. Textures are a modified 8-bit format that I haven't fully worked out yet.
The Wipeout series has been interesting. Wipeout and Wipeout XL use almost the exact same data types between them. There is some simple LZSS-type compression. I'd assume that the engines are not very different. Basic track data is stored as a linked list of quads with some fixed data that I dont know and some translation info that I haven't worked on. Wipeout 3 is a little different and stores data in a large file that looks compressed. Wipeout Fusion on PS2 has been a lot of fun. I found all the music in uncompressed 48khz 16-bit stereo RIFF WAV format. I haven't fully reverse engineered the data store format, but it's pretty straightforward.
Of course theres R-Type Delta and Final and Metal Gear Solid which I've talked about before.