Stockholm-Bergen (direct flight)
Gøteborg-Bergen (Not direct flight. Can be combined with train / bus)
Reykjavik - Bergen (direct flight)
København-Bergen (direct flight)
Billund-Bergen (direct flight)
There are also a number of direct flights to Bergen from the rest of Europe. http://www.avinor.no/lufthavn/bergen/direkteruter
Through SAS you can book group travel (minimum 10 people).
To order group travel you can contact SAS at e-mail firstname.lastname@example.org and enter the booking code BECUPNO.
One of the advantages of group booking is that you can rename the tickets until the day the tickets are issued.