For multi-disc sets, SlimServer supports the DISC and DISCC tags that indicate
the disc number and total disc count, respectively.  I would like an additional
tag, DISCNAME (or DISCTITLE), that could contain the name of a particular disc
in a multi-disc set where each disc has a distinct name.  For example:

ARTIST=Smashing Pumpkins
ALBUM=Mellon Collie and the Infinite Sadness
DISC=1
DISCC=2
DISCNAME=Dawn to Dusk

ARTIST=Smashing Pumpkins
ALBUM=Mellon Collie and the Infinite Sadness
DISC=2
DISCC=2
DISCNAME=Twilight to Starlight

For display purposes, slimserver could show:

Mellon Collie and the Infinite Sadness (Disc 1 - Dawn to Dusk)
Mellon Collie and the Infinite Sadness (Disc 2 - Twilight to Starlight)

in the album list for single mode, and:

Mellon Collie and the Infinite Sadness

for set mode, as it already does. The track listings would probably have 
just:

...from Mellon Collie and the Infinite Sadness (Disc 1 - Dawn to Dusk)

in single mode and:

...from Mellon Collie and the Infinite Sadness (Dawn to Dusk)

for set mode.