Converting a White background to Tranparent (Photoshop)

Here's a great tip if you have to "peel" a white background off an image which is much cleaner than using the magic wand, as the magic wand often leaves either a halo or a jagged/untidy edge.

1. copy the image to a new layer and delete the background layer
2. copy the image to a new layer again and INVERT it
3. copy the inverted layer into the clipboard, and switch off its visibilty for now
4. go back the the +ve image and create a layer mask
5. press ALT whilst clicking on the mask thumbnail
6. paste the inverted image, then click back to the image thumbnail in the layer palette
7. duplicate this new layer until necessary (5 times?) and delete the inverted layer you created at the start
8. merge down the layers one by one (Ctrl-E) choosing to "apply mask" each time