Condition of common areas in your building: http://dom.mos.ru
Road issues, eg. open manholes or broken traffic lights: http://doroga.mos.ru
Other problems: gorod.mos.ru
There are reports that the authorities do react to complaints left there. I’ll soon be testing it on my building, where the entrance hall is a mess, walls are full of graffiti, and paint is falling off the ceilings. Yes, that’s the one where I have my apartment that’s available for rent although I should probably not be mentioning it in connection with the above.