Unfortunately there are no physical tourist information where you can walk in from the streets and ask for turistinformation as you know it from the rest of the world, neither in Kangerlussuaq or Sisimiut. Both the local and national public authorities have decided only to have a digital touristinformation. So when you get to Kangerlussuaq or Sisimiut, it is wery important to search the internet for possiblities before you leave home. There are few private operators with their own "turist"office, that have limited promotion of touristinformation, but it is ofcourse not a 100% objective, because they want to sell their own products.
The national digital touristinformation is found on www.greenland.com and covers all of Greenland, and is a super website, and it havewon the Webby Awards here in 2012, the oscar of the web.
For Qeqqata Kommunia, Maniitsoq, Sisimiut and Kangerlussuaq and the smaller settlements, you can find the local touristinformation on www.arcticcircle.gl and is also quite new and wery fine.