Geek knitting ideas.

1) Emission Spectra Scarves. Or Absorption spectra ones if you're after something more colourful. via @davedevereux.

2) 3 colour Brunnian link (not a knot) neck warmers / bracelets. Wikipedia link via makyo.

3) A double walled tubular scarf with two side scrolling levels on it that actually scrolls.
Look it works in my head, okay.
Knit a few loooong rows of brown. One or two of green. Quite a few blue. Then a few brown.
Fold in half width ways, and stitch together, such that the join helps stop the tube rotating.
Sew on a load of felt bits representing objects from Sonic on the green stripe edge, and Mario on the other.
Pull one end through the middle, and seamlessly stitch to the other.