The people who did a really brilliant job with setting up Atlantis Madagascar in Anakao (which they have now sold) have just opened a new backpackers hostel in Tana with a Mexican Restaurant and bar called Madagascar Underground. This is something that is really in demand in Madagascar, a place for travellers to meet to hang out, share stories, share travel costs etc... It's a great idea... The website isn't finished yet but you can contact them on their Facebook page so have a look for Madagascar Underground on Facebook.
And for the record, I have no connections to this establishment I just know that these people run a good show, they did a great job with Atlantis in Anakao so let's hope this is equally good :)