Greg's Hinged Accessible Extruder

If you're looking at this, you probably really want this version that has better access for cleaning the hobb and also a guide for the filament integrated with the idler:
http://www.thingiverse.com/thing:17030

If you are interested in the stages of development, read on for the details of this version:

This is an update to my Accessible Wade's Extruder.

The idler is now hinged using an M3 screw.
I have also added support for the central part of the 608 idler so that there is no need to use washers to space the bearing away from the plastic.

I have been using this design for a while now and love it.

Changing filament is a simple as compressing the spring then whipping out the old filament and poking the new one in.

UPDATE: 6 Aug 2011 - Add arcol (cory75 thing:10532) and wildseyed hotend mount options. Im not overly happy with the asymmetry of the arcol option.