[deSousa]

Hi there Dale, my contribution:

Magma is pretty much a concept band. Beyond MDK you may also consider:

Köhntarkösz - 1974
Ẁurdah Ïtah - 1974
K.A. - 2004
Ëmëhntëhtt-Ré - 2009

Ẁurdah Ïtah and MDK are movements 2 and 3 of a larger set called Theusz Hamtaahk. The first movement was never recorded.

There are 2 concept albums by Hawkwind based on Michael Morcocks's writings:

Warrior on the Edge of Time - 1974
The Chronicle of the Black Sword - 1985

Though the last one may not qualify as prog...

And speaking of Hawkwind:

Robert Calvert - Dr. Lockheed and the Starfighters - 1974

The first two LP by Area are concept albuns:

Arbeit Macht Frei - 1973
Caution Radiation Area - 1974

More from Italy:

Museo Rosenbach - Zarathrusta - 1973
Blocco Mentale - POA - 1973

Within Krautrock I only know nof this strange effort:

German Oak - German Oak - 1972

But there's more from Germany:

Eloy - Dawn - 1976
Eloy - Ocean - 1977
Eloy - Colours - 1980
Eloy - Planets - 1981
Triumvirat - Illusions on a Double Dimple - 1973
Triumvirat - Spartacus - 1975

José Cid made two concept albums, of which only one became globally notorious:

Cantamos Pessoas Vivas - 1975
10 000 Anos Depois Entre Vénus e Marte - 1978

That's all I can remember for now.