I've already posted in here but I figured I'd offer up some more:
The Verve: "The Drugs Don't Work" I play it more like Ben Harpers cover of it...
James Morrison: "Wonderful World"
Alanis Morissette: "Ironic" and "You Outta Know"<----- The girls always seem to get into that one. haha
An acoustic Sheryl Crow version of "Sweet Child of Mine"
"Good Love is on the Way" by John Mayer... A cool song on acoustic.
"Something's Missing" by John Mayer... not very convenient for campfire use since it's played in a weird tuning..... But it's a killer song to play when hanging out with friends.
"Cortez, The Killer" me and my best friend love playing this one with one electric guitar and one acoustic guitar.
And a whole bunch of Dave Matthews stuff... College students are pretty well versed in his stuff so it's a natural fit that they love to hear it while around a campfire.... Some of my favorites that I play often of his are:
Grey Streets
Jimi Thing
Trippin Billies
Ants Marching
Gravedigger
Granny
Warehouse
Two Step
Dancing Nancies
So Much To Say
Too Much
and What Would You Say...