customise osx's startup screen
Over at Creative Bits, there is a handy tutorial showing you how to customise the background image for your Mac’s startup screen. It seems a shame that this feature wasn’t built into the system preferences amd is reliant on you substituting the real ‘Aqua Blue.jpg’ with another image which is renamed to get the desired effect.
As with all command line tweaks - be sure to make backup copies of all affected files in question before commencing!
Maybe this deserves a few lines of feedback over at Apple. If enough people make their voices heard this may be changed in a later incremental update.