Iceland's so small there really isn't any monster.com type job listing site. Jobs that are advertised are generally in the newspaper, so you can find some on these two newspaper sites:
as you see, not many jobs listed, and at the moment, none are graphic designers.
If I were looking for a job like that in Iceland, I'd probably just do a net search in English and then send emails to offices I found that way. If they've got an English website, they're presumably not against hiring people who speak English. If you have a good online portfolio, you never know what might happen.
it'd also be good to plan a trip to Iceland so you can write to them and say "here's my great work, I'd love to talk about career opportunities at your place when I visit Reykjavik on these dates"
