Not Franco-Belgian, but worth checking out. Daniel Torres "Roco Vargas" adventures published by Dark Horse Comics, a very nicely drawn spanish comic. It's available in a thick hardbound album.
http://www.marsimport.com/display_comic.php?ID=2059
Moebius and Jodorowskys "Incal" stories.
http://www.humanoids-publishing.com/news/news.php?id=119&idx=10
Was published in the Heavy Metal magazine and some albums.
"The airtight garage" by Moebius is also available in english, published by Marvel Comics alongside a whole bunch of his other stories.
http://www.lofficier.com/moebiusjm.htm
Freddy Lombard (Tintin look-a-like) by Yves Chaland.
http://www.humanoids-publishing.com/products/prod.php?id=142
If adult comics is ok, then the Italian Milo Manara have several album published in english.
http://www.overseascomics.com/milomanara.html
Several of Enki Bilals beautiful stories is published in english.
http://www.humanoids-publishing.com/products/prod.php?id=167
Megalex is yet another work from Jodorowsky drawn by Fred Beltran.
http://www.humanoids-publishing.com/products/prod.php?id=168
Vittorio Giardino have some of his works translated to english.
http://www.nbmpub.com/comicslit/giardino/prag.html
Vicente Segrelles astonishing oilpainted comics in english.
http://www.segrelles.com/works/mercenary00.htm
Sorry about including other than just Franco-Belgian but these are really worth looking up, imo.