I don't think there's a complete list anywhere. So here's a pretty big one.
rust - Rust 24-hour partyline
rust-internals - Compiler hackers
rustc - Focused discussion on rustc internals
rust-libs - Focused discussion on rust std libs
rust-bots - Status updates
cargo - Anything about Cargo
servo - Anything about Servo
rust-tls - Implementing TLS in Rust
rust-triage - Bug triage room, usually empty
iron - The Iron web framework
mio - The mio I/O library
hyper - The hyper HTTP library
Also the korean channel, #rust on the ozinger network.