rEFInd iSquish boot Theme
rEFInd is a boot manager that works with PCs and Macs, and is able to boot virtually all modern OSes. It features many improvements over native bootloaders and it is highly configurable.
For more information on how to install and configure rEFInd (and this theme) please visit rEFInd's homepage http://www.rodsbooks.com/refind/
This theme is very unorthodox. rEFInd has its theming limits and such boot menus are simply not possible using the conventional rEFInd theming options.
In order to archive this kind of menu all the icons of the theme are drawn from the background image (including drive "icons", in this case Psi gauges). For overlays instead of the dull glowing balls under icons or retangular squares on top of them we have images that superimpose on the background. For this to work all drive icons (present) must be transparent images. The result is the boot menu/image you see above.
The downside of this kind of theming is that the UI is "hardcoded" to a predetermined number of drives. Of course you still can boot any bootable media inserted normally, but the whole thing gets shifted and it won't look good.
This is not a problem for me as 99.9% of the time I only have these three boot options (OSX Windoze and Linux). It shouldn't be a problem for most.
The theme's resolution is 1280 x 800 but one can easily mod it to other resolutions using some graphical editor, such as good and ol' Photoshop. PSD "template" files are included.
Get it here.