Off the top of my head (and some stuff most certainly wrong :-) ...

S/PDIF - Sony/Phillips Digital Interface, the "original" specification for digital audio transport over copper coaxial cable. Describes the framing format as well as the physical transport medium.

AES/EBU - Specification for digital audio transport over balanced (XLR?) cable. Framing format is very similar to S/PDIF. "Mostly" interoperable with S/PDIF framing if you mangle a few bits here and there.

IEC958 - International Engineering Consortium specification describing a digital framing format only. Basically a cleaned-up S/PDIF specification without the physical medium description.

TOSLINK - IEC958 over optical coaxial cable. Popular for consumer gear (eg DVD, Minidisc)

ADAT - Alesis' standard for 8 48khz channels over optical coaxial cable. From what I understand the data stream pretty much looks like 4 TDM'd IEC958 streams. Some vendors offer a "modified" ADAT framing to carry 4 96khz channels rather than 8 48khz channels - same bandwidth, just multiplexed differently.

-Dan
(goemon at anime dot net)