Hello,
In Switzerland, the only real cels shop is mine :
Animanga. Else, the following shops carry some
cels from time to time : Manganime (Lausanne),
Paradoxe Perdu (Geneva), Imagination (Geneva).
9eme Art and Mix-Image had some long ago but
not anymore.

In France, the following have some cels from time
to time (mostly on anime popular in France) :
Atomic Club (Paris), Red Sun (Paris), L'antre
du Sorgleux, Fan Japan (they had the animefancels 
website but the shop is now closed definitively)
and a few others.

In England, Forbidden Price  err.. no, Forbidden 
Planet (London) has some but I don't think they
got any new ones since at least 5 years...

I know that there is some anime shop in Italy
that have cels (one in Rome at least) but I
don't have the names sorry.

Cheers,
Yann Stettler