'Monkey Man'
'Jump into the Fire'
'Atlantis'...
and don't forget Jerry Vale's memorable... 'Pretend You Don't See Her' ;) The songs go so well with the movie it's scary.
That is one of the great uses of a soundtrack. In the beginning, when the mafia was still primarily about gambling and prostitution, the songs were romantic. Then as drugs started entering the picture, the music reflected that, right up to the ending with Sid Vicious.