Replying to Help Me Find Music

So, I'm at that stage where I'm not sure what artists/songs/genres to turn to. Usually I like good underground hip-hop, but lately i've started liking a bunch of different stuff such as:

Death Cab for Cutie - Soul Meets Body
Bright Eyes - First Day of my Life
Bright Eyes - The Calendar Hung Itself
Placebo - Special K

I was never big in to this area of music (I want to call it alternative, but people take their categories of music way too seriously)

So, If you can figure out songs similar to those (doesn't have to be same artists) and tell me, i'll download.