I often order large prints and usually, the image is trimmed down because the printer service applies a 2 or 3mm bleed, which can't be avoided. I'd like to have a feature in the crop tool allowing me to enter the value of the bleed (usually 2 or 3 mm) and the desired print size and displaying the resulting bleed zone as a grey area in the current image (or displaying a line showing where the image will be trimmed). This would be very useful when preparing a file for an external printer service and adjusting the image in order to take the trimmed area into account.
Of course, this feature should be available in the development module while using the crop tool.
I guess this would be useful for all the users who send their images to a printer service.
You should make your enhancement request at the LR feedback site: