Not sure if you used any of these as I am a newbie to this site...
For Powder Keg, what about going old school? Not country, but it's got a little bit of the right vibe going on...
Mississippi Queen by Lynard Skynard
Travelin' Band by Creedence Clearwater Revival
For the rest, some of it's mainstream, some of it's obscure, some of it's fun, but I think any one of 'em will fit. Nothing too hardcore...
Atom Bomb by Fluke
Special by Garbage
Get the Cool Shoe Shine by the Gorillaz
Take me Out by Franz Ferdinand (that song from the PSP commercial)
Extraordinary by Liz Phair
Sunday Morning by No Doubt
Fortune Faded by the Red Hot Chili Peppers
Why Can't We Be Friends? by Smashmouth
Get Free by The Vines
Callin' Out by Lyrics Born (that song from the Diet Coke commercial w/ Adrian Brody)
Feel Good Time by Pink (from the Charlies Angel 2 soundtrack)
Three Little Birds by Sean Paul & Ziggy Marley (from the Shark Tale soundtrack)
Let's Get Retarded by the Black Eyed Peas
The Hit Song by DJ Format ft. Abdominal
Kickstart My Heart by Motley Crue
Top of the World by Shonen Knife
Are You Gonna Go My Way by Lenny Kravitz
All I can think of for now...