I can't let this thread go by without plugging :
"Morning Afterglow" by Electrasy...!
And also "Sing," "Turn," and "Side" by Travis. ("Sing" in particular is amazing!)
For up-beat, pop-punk (think Jimmy Eat World I guess) I would also recommend any songs by the following bands:
-Dropkick Murphys
-Bowling For Soup ("Self Centered" is great!)
-Me First and the Gimmie Gimmies
For things a bit slower and peaceful...
- Secret Garden (especially "Dreamcatcher" and "Sona")
- Jann Arden (she is an AMAZING singer/song-writer...she had that popular song "Insensitive" from years back...but her cd "Happy?" is awesome)
- Sarah Brightman's cover of "Scarborough Fair" is really pretty too....