Ubuntu 10.10 PPA: https://launchpad.net/~t-w-/+archive/ppa (this does not include the templates, as package can't install to the users Templates folder. They are available as separate archive, see Downloads).

extract-background-context:
    Expects one screenshot with white, and one with shadow-color (usually black), background as input. Puts out a PNG image with transparent desktop. This is useful for evaluating wallpapers that should go well with panels and themes other than the one you are currently using.

extract-background-context-gnome
    Like extract-background-context, but automates changing background and taking screenshots. Needs to be used from within a GNOME session.

to-common-resolutions:
    Expects an image as input and crops/resizes it to several common screen resolutions. Output is saved in a directory "name_resolutions" where the name of the input file sans extension takes the place of "name". Filenames inside the directory specify the resolution, e.g. "2560x1600.png". The input image will be copied unprocessed but renamed, if it matches one of the resolutions.

context-to-common-resolutions:
    Expects an image with transparent background, that may contain panels, icons and windows (like extract-background-context produces) and crop/resizes it to several common screen resolutions, while doing something hopefully sensible with the content. Same input/output handling as to-common-resolutions.

combine-per-resolution:
    Combine pairs of images of matching resolution. Expects 2 paths, either to a single image file, or a directory containing images. Each image found at, or within, the first path will be combined with all images of matching resolution found at, or within, the second path. The first path will be used for the lower layer, the second path for the upper layer, when compositing.

Templates:
    An SVG template for use with Inkscape and an XCF template for GIMP. Both have a 2560 x 1600 pixel canvas to use the largest commonly offered resolution, currently. "Passepartout" layers allow to see how things will look when this space is cropped to conform to other common aspect ratios. This simulates the effect the "Style: Zoom" setting in "Appearance Preferences: Background" will have: the image is scaled up or down such that it fills the screen without distorting it. If the aspect ratio of the image is wider than that of the screen, it will be scaled to the same height and the areas on the sides will be cropped. If the aspect ratio of the image is taller than that of the screen, it will be scaled to the same width and the areas on top and bottom will be cropped.