Having spent 2 years in Stavanger, Norway let me commend the Irishman Pub which has a traditional session/singaround once a month. The house band -- The Harbour Folk Band -- is comprised of a mix of Norwegians and expats: 2 CDs available for purchase there.

If you are feeling adventurous and looking for something different Stord Island, just south of Bergen, is home to the group Storm Weather Shanty Choir. They have performed in the States. Saw them on stage in Stavanger during the Tall Ships Race in 2011. A cross between Great Big Sea and a heavy metal band (in appearance at least).
Med venlig hilsen

Brian