I have found when printing PLA, on some parts where even cooling is critical, the stock blower duct on the Replicator 2 is uneven. Favouring right to left movement, rather than left to right on the X axis. So I set about designing a new blower duct that directs air directly downwards for more even cooling. This design has gone through several iterations, but the latest one appears to do the trick.
As proof of concept I printed an enhanced version of the Make Magazine Torture Test using my redesigned blower duct and I think the results speak for themselves. There was a bit of excess stringing which obscures the results, but no dangling from the overhangs except the arch which had a modest amount.
UPDATE (Aug, 31, 2013) I added a small gusset to the design to stiffen it when printed in Nylon.
I printed this in Nylon, which seems to handle the heat of being next to the nozzle. Cut off the tab support structure when its done - its only there to steady the duct while printing.