I would like to contribute to the ongoing project but am currently having trouble taking good photos of the covers (labels are a cinch) and wondered if some of the contributors would like to share some tips on how to get a good photo.
I have the lighting ok now (using natural light, no flash) but my main problem is getting a perfectly square image to crop, quite often the image is distorted due to a slight angle.

I got a great tip from Shooky for fixing problems like these with Photoshop:

Use the filter found under Filter > Distort > Lens Correction.
The Vertical Perspective and Horizontal Perspective sliders can be used to correct a tilted image. The Remove Distortion slider can be used to fix the 'barrel effect' you can get when photographing items.

I take pictures of the outer and inner sleeves in daylight in the attic with a mini-tripod (the adapter on the camera is used for digiscoping, never mind that!). I set the sleeves as much upright as possible against a white door and use a distance that does not force me to zoom out (as this causes barrelling). The shutter speed is between 1/10-1/50, so I use the timer to take the pictures. This really is necessary because I ended up with far too many shaky or blurry pictures, even when resting the camera on other objects. Sleeve details and labels I put on the scanner, which produces better quality output than the digital camera.

It may help to first set the white balance of your camera using a plain A4 sheet, certainly if you take pictures with the lights on. That may save you time tweaking your output in Photoshop.

without wishing to open any floodgates, i'm willing to help if people can take pictures but are not equipped with photoshop or the time/technique to see it through. as with most things, however, the source picture is the key factor and lo-res, blurred pictures, or those with flash glare etc, will not be miraculously saved. PM me if you need help or want to send test pics for evaluation.