I think this is best:

largest 4x3 (the ones like 1600x1200)
largest 5x4 (the ones like 1280x1024)
largest 16x10 (the ones like 1680x1050)

etc.

The OS shrinks the image itself. What matters is the aspect ratio.

Also, it's even nicer when the composition differs slightly between one aspect ratio and the next.

variety is the spice of life

Personally I like to make up all the sizes as I add my web address.

I don't see much of a point ... buuuuut ...

posting them in widescreen and standard ratios is one I'd strongly suggest ^__^

yes


unless they are in the right size, the sharpness will be gone,

especially with spaceart

the stars will be gone in a starfield when you downsample a 4000x3000 to 1600x1200

optimum sharpness for each resolution , essential ,

I like predone cropping because you can't really crop a full screen ratio wallpaper to fit widescreen unless the wallpaper being cropped is hella big (like, bigger than 1440x900). It's way hard for me to find (good) widescreen wallpapers these days. I'm not saying a zip for like...ten different sizes, but maybe a big size for widescreen AND fullscreen, and not just full screen.

Depends really. I mean, I wouldn't really expect anyone to have a screen resolution of 1600x1200. The majority of people have 1024x768 max.

I said no, b/c people can do it themselves if they really want to, but I always have someone asking for another size. So I do it sometimes, not always.