Paillier Cryptosystem - Practical applications? I wonder: are there any real-world practical applications using the Paillier cryptosystem , as introduced in [1], or some derivations of it?

I'm aware of quite a few schemes proposed in literature how to use it for voting, zero-knowledge proofs and such, and also of many prototypical implementations online, but I can't seem to find any application where a Paillier(-based) scheme was effectively used...(also, I don't think there is any standard defining it).

[1] Paillier, Pascal (1999). "Public-Key Cryptosystems Based on Composite Degree Residuosity Classes". EUROCRYPT. Springer. pp. 223–238
Yes, for example CryptDB uses the Paillier cryptosystem to implement homomorphic encryption for columns that require it. See CryptDB: Protecting Confidentiality with
Encrypted Query Processing (pdf) for a description.

Whether you consider that use "effective" is another matter. Earlier this month there was a back and forth between the CryptDB developers and some Microsoft researchers who claimed to have several attacks on CryptDB. However, as far as I can tell they were on the other forms of encryption CryptDB uses.