Lost in it all is the fact boston has got themselves in the best situation.. If they get healthy they will easily make the playoffs and have a good run.. On top of that they will likely get a top 3 pick. Has that ever happened before? Couldnt be in a better situation.
Well, the Isles traded the 2nd overall pick in 2001 to Ottawa (along with Chara) for Yashin, but that was at the Draft.
As mentioned, the Colorado Rockies traded their 1983 first round pick in October of '81 to the Isles for Bob Lorimer and Dave Cameron.
The Leafs traded their 1991 first round draft choice in October of 1989 to New Jersey for D Tom Kurvers. Toronto ended up finishing 3rd last in 1991, and the Devils selected Scott Niedermayer.
In June of 1986 the Canucks traded Cam Neely and their 1987 first rounder to Boston for Barry Pederson. The Canucks too finished third last and Boston chose Glen Wesley- who actually played the most regular season games out of anyone from that first round.
However, the most famous example is the California Golden Seals/Montreal Canadiens trade of 1970. The Seals, one of six teams to join the league in 1967, traded their 1st in 1971 to Montreal for Montreal's 1st, 23-year-old top prospect Ernie Hick and cash.
While the Seals were terrible, the fellow expansion Kings and aging Wings were also expected to finish at the bottom of their respective conferences. Canadiens GM Sam Pollock shipped popular center Ralph Backstrom to LA for basically nothing, and traded three younger forwards to Detroit for Frank Mahovlich.
When the dust settled on the 1970-71 season, the Kings (63 points) and Wings (55 points) both finished well-clear of the Seals (45 points). Montreal ended up using 'their' first overall pick on young Guy Lafleur.