Nerd punk at it's finest. I guarantee you'll find a song by these guys you'll fall in love with.
Jesse Michaels is the man. He was also the frontman of Operation Ivy, which was arguably the more well known band (if you're not familiar with Op Ivy either, check them out). Prepare for some rad lyrics.
These guys are based in Detroit. Amazing ska-punk songs with an unfathomable amount of energy. I saw them live and got moshed so hard I flew. Great stuff.
Here's a complete turn in the opposite direction. This guy's all about folk band and acoustic guitar music, and everyone one of his albums are pure genius. Check out his stuff when you're feeling a bit on the lighter side.
You've probably heard this guy's music before in the Shrek films, and probably tons of other movies too. One of the most pure and amazing artists I know, give his albums Beautiful Freak and Electro-Shock Blues a few listens through, and I think you'll see what I mean.