Pretty much any old thing that intrigues me, really:
Old consoles (NES/SNES, Famicom, Genesis, Saturn, Playstation, N64, Dreamcast)
Old computers (PDP-11, C128, MSX2, Tandy 1000RL, 386DX-40, any Mac that can run Classic Mac OS)
Records (all my favorite bands have most of their best releases back in the '70s anyway)
Weird thrift-store video finds (anything that looks like it could've been on MST3K)