The biggest artist right now in Colombia for sure is Juan Esteban Aristizábal Vásquez or just simply: Juanes.
Since splitting with his band Ekhymosis, he has come a long way. I remember my brother (after living in Guatemala for a year) told me one day that he was going to a concert of some guy named Juanes, whom was performing (probably for the first time) in Amsterdam. My brother in the middle of mainly Latin people enjoyed a great concert but it took many years to for me to get familiar with his music. Since hooking up with my Colombian lady, I am getting a daily portion of his songs though ;).
My personal favorite is Mala Gente:
Most non-Latins will automatically get the Latin feeling when listing to La Camisa Negra:
Just kidding, this of course was not Juanes…the song has been played so often though that I had to put another version here not to get annoyed myself haha
and to finish one of his newest songs that I hope will make it also to the motherland; Me Enamoras: