After some difficulty finding it , I visited Fantasiapelit. Great place! Their selection of d20 stuff (not to mention a huge range of other RPGs, Mass tabletop, CCGs, and all other sorts of games) was incredible. All the major d20 publishers, with nearly all their products. Plus a huge range of dragonlance/FR etc novels (in English). My only dissappointment was not finding bad axe game's stuff, asI was prepared to buy their dwarf book.
I did come away the Vault of Larin Karr...
I'm going to go out on a limb and say that Fantasiapelit in Helsinki is the best gaming shop east of Berlin (well, unless you go waaaay east).