I've been listening to Mahler's 7:th symphony. It is pretty cool. I like how it sounds modern. It's not easy though and I read that when it was first premiered in 1908 people found it confusing. I also think it is confusing but I don't care.
The whole symphony ends in an interesting way. Before the final chord in C major, Mahler throws in an C augmented chord (with a G#), just hanging in the air and creating a strong feeling of suspension. And then, boom!, comes the C major chord and the whole thing is over. Nice!
The Beatles also uses an augmented chord to create suspension in the beginning of the song "Oh, Darling".