Most of these are not going to work for a laptop skin, the resolution is too small. But they should make great skins for smaller devices like iPods, PSP’s, cell phones or other mobile gadgets.

JuneWind - 30 colorful wallpapers in several resolutions

Apple Wallpapers - Nice collection of 30 Apple inspired designs

framebox - disruption rendered series

xshock - great collection of grungey and similar styles

fantasyartdesign - cool designs worth a look

moving insect - great designs, don’t miss this one

Mobiusco - over 80 designs, another worthwhile visit

And lots more at Flickr here and here!