http://www.youtube.com/watch?v=ffYm-lRohCg - Acoustic covers of his own ska-punk songs. Good lyrics. I'd say good voice too but I'm biased.
http://www.youtube.com/watch?v=Wf_s5pWs2-E - Are they popular? Hell if I know! Have some anyway. Electronic w/ vocals and some acoustic guitar.
http://www.youtube.com/watch?v=SJ4Bq6DRpBk - Instrumental rock. I just find the music beautiful. Also does http://www.youtube.com/watch?v=F8Rt7u7fnIk if you're into that.
http://www.youtube.com/watch?v=Wbhgzip6sx0 - Chiptunes! I suppose they may be popular in the chiptunes scene, I dunno, I just like the old-school feel. Amazing how awesome music from old games could be despite such limited sounds.
http://www.youtube.com/watch?v=rgjvEDlktcc - Post-rock interpretations of Zelda music. I already liked Zelda music to begin with, post-rocking it is just damn fun.

They're just demos but he's very close to release a final album.
http://www.youtube.com/watch?v=RI8SoWxphHc - Interesting indie-rock. Vocals, mandolin, violin, cello, standup bass, and drums. I like them instruments. http://www.youtube.com/watch?v=cpJEuQkw9cQ Crazy Princetoners.
http://www.youtube.com/watch?v=2a4gyJsY0mc - Rock with a random edge. I find them highly amusing (though their recent albums have been disappointing). I know I've posted this video here plenty of times before, maybe they're popular now!
http://www.youtube.com/watch?v=KroMcTiH_OQ - If you didn't realize I love Zelda music. Zelda trip hop!
http://www.youtube.com/watch?v=6xbgjYyH47k - (instrumental)Metaaaaaaaaaal. I don't normally enjoy metal but this intruiges me.
http://www.youtube.com/watch?v=9-f1ZqUxfC8 - Crazy rock. Love the mix of genres. http://www.youtube.com/watch?v=cZLmCBkbKJM
http://www.youtube.com/watch?v=3Nrm4H7FJGw - I've posted it before and someone else in this thread posted it. Fantastic jazz, great atmosphere.
http://www.youtube.com/watch?v=EpDXra9Zbk4 - Heard this while drinking at a bar on Ko Mak. SoundHound is awesome. Acoustic, soft female vocals. I'm quite sure it's somewhat popular in Asia but you're mostly not Asians.
http://vasudeva.bandcamp.com/ - Some more instrumental rock, nice and peppy. Free download.
http://www.youtube.com/watch?v=J_i9fFR9lJE - Can't so no to a badass metal cover of a great song from a great soundtrack.
http://www.youtube.com/watch?v=yzC4hFK5P3g - J-Pop. What can I say? I like it weird and colorful. Crazy dancing faceless grandma is best grandma. Disclaimer: Do not try puking birds or farting rainbows in real life.
ARIA soundtracks: http://www.youtube.com/watch?v=6UWiFu5kOCY http://www.youtube.com/watch?v=4wHyKw1jD8c http://en.wikipedia.org/wiki/List_of_Aria_soundtracks. ARIA the Box is incredible. Acoustic guitar with a Spanish flair I suppose and piano music. Some jazzy stuff and anime openings/endings too.
http://www.youtube.com/watch?v=lh9a5kJuz_0 - It's the only song I've actually heard by her but I like it (though she likely didn't compose it). Piano + Vocals + Chorus, dreamy music.
To someone earlier in the thread saying that just listening to OSTs isn't a music fan is just so utterly stupid, especially considering it has no genre limitations. It's worse than saying anyone who listens to X genre isn't a fan of music because in reality OSTs can be of X or Y or Z genre. Or all 3.
Bandcamp is a wonderful place.
And have some http://www.youtube.com/watch?v=soKmGKAVUk4 too, probably somewhat popular though. lolpokemon
That post was long.