You guys (OP included) are just listing your favorite songs. When I saw this thread title I was thinking of absolutely classic songs that everyone should be forced to hear at least once in their life. Granted, technically a lot of songs could qualify because there is very little to lose in having to listen to a song, but its my intuition that the songs in this thread should be extremely, extremely good. Like one in a million or something. Very few of the songs mentioned in this thread qualify and I'll have to retract my suggestion of Refused - New Noise in light of my new qualifications.
Another quick note: I hate that rendition of Pachelbel's Canon
I stand by my recommendations of Cantus (in memory of benjamin britten) and Summa. FWIW I think Part (umlaut over the a, pronounced [pear]t) is the most brilliant composer I've ever heard.
Cantus:
http://www.youtube.com/watch?v=e348n660zrA
Summa:
http://www.npr.org/templates/story/s...toryId=5495725 (I don't like this version, a much better one can be purchased on itunes as part of the sanctuary CD)
if you like my suggestions you can look forward to a thread I will make soon on contemporary music. In it I hope to discuss Part, Reich, Takemitsu, and a whole bunch of others.