this thread has probably been done countless times before. Whatever.

The first band that springs to mind is Chumbawamba. From anarcho-punk:

http://www.youtube.com/watch?v=kWLHpuLrpyk

to pop:

http://youtu.be/girA7GS9hDg

and finally to grassroots folk:

http://www.youtube.com/watch?v=XEVVkaQw9fo

Prefer their earlier stuff OBVS.