Lulzbot TAZ 3mm Filament Straightner
Those small spools from some sellers on Amazon are very small and put a very tight curl in the filament that gets worse as you use the spool. This makes the feeder tube want to curl around the frame and has caused issued with prints occasionally.
This thing will fix that problem by straightening the filament as it enters the feeder tube. Adds a bit of drag to the filament but the extruder does not seem to care.
Should be adaptable to other printers.
Here it is in action: http://youtu.be/C29wdVIwqf4
update: 7/20/14
Added v2 of the base plate. this version bolts to the 20x20. it also has holes to mount the added spool end guide. This keeps the filament contained.
update 7/21/14
added picture showing filament before and after going through my straightener.