Piano

Call the Salvation Army (Armee de salut) who have a huge warehouse to sell on goods near the Canal, or les Petits Riens who also sell on goods in their warehouse on rue Americaine, Ixelles. They will also take your books and records.

Both of these give accommodation and support and give work to homeless men.

Freecycle? http://groups.freecycle.org/Brussels_Freecycle/posts/all

Brussels selling group on Facebook?https://www.facebook.com/groups/392213734210774/?directed_target_id=3922...

if you want to try selling it contact your local Troc but it can be a hassle to sell it there if you're leaving