A pple has once again updated its refurb offerings for the Apple Store. As of this writing, there are 40 GB iPods (non Click Wheel), 12" and 14" iBooks, several models of 12", 15", and 17" PowerBooks, three different Power Mac G5 models, iMac G4s, eMacs, and AirPort Extreme cards.
These products tend to go pretty fast after we post the announcement, so availability will depend on when you visit the page.
You can find the list of refurb items by visiting the Apple Store Hot Deals page, and clicking on the "Special Deals" link.