"It seems that Sirius knew what he was doing. You are the rightful owner of number twelve, Grimmauld Place, and of Kreacher."
-- Albus Dumbledore (HBP3)
Sirius’ will was discovered a few days after his death. He left Harry everything he owned, including his house, personal possessions, and Kreacher. (HBP3)
Harry unknowingly inherits a Horcrux, the Slytherin locket.
While it's sweet that Sirius leaves everything to Harry, it would have been nice if he left some gold to Lupin too. After all, this is inheritance, not charity. Harry has a pretty good amount of gold, and he is yet to build a life of his own; Lupin however can't even get a job because of his lycanthropy.