Bicubic and Bilinear resampling exist on many photo and video editing programs (Photoshop and VirtualDubMod is two of them). They give specific smoothing and/or sharpening effect when you have resized your image. Bicubic is very good, especially on VirtualDubMod, when you want the image to look clear, not so blurry and still get the screen-size you want. ^^
Oh yea, there's also Pixel Size resampling too.
Paint Shop Pro 7 has it and it's excellent for sprites (just remember the 200% / 50% resizing rule).
That is, if you don't use MS Paint of course, because you can do it there too. X3