After almost two years of searching I finally found it: Russia!
http://gibdd-baza.info/

Before checking a plate, you need to select the oblast. It runs on the same engine as the Kazakh site, but is a bit harder to use...I at first managed to crib results only by searching alphabetically, but then I got it. After selecting your oblast, you type the plate in this format: "lowercase letter-three numbers-two lowercase letters."

I hope it's not too much of a hassle for you to quickly switch to a Cyrillic keyboard...