Heartwarming / The Imaginarium of Doctor Parnassus
A meta example. The three replacement Tonys gave their salaries to a trust fund for Ledger's daughter, Matilda, due to Ledger's will having been written before she was born.
The casting of Depp, Law, and Farrell in and of itself counts because the three of them were all good friends of Ledger's, something that Gilliam took into account when casting the parts since he didn't want just anyone in the roles (considering people like Tom Cruise had already shown interest).
Also, the cast got tattoos of hearts on their hands in memory of Heath Ledger and there's a point in the movie where you can see the tattoo on Lily Cole's wrist.