@Jan:
that first scarf that you linked is just awesome. My apprentice here at the office is a relatively new knitter and wants to make a scarf. She can knit, she can purl and will have to built some endurance.
@megan:
I like scarf with end pieces, meaning: make a complicated pattern (Any you like and consider fitting) and make about a handspan of that. Then continue plain, e.g. garter stitch or stochinette stitch with garter stitch edges (or maybe you can run your pattern as an edging?) or ribbing for example 2 by 2 or 1 by 1 or 3 by 3… Then when you are almost done, repeat the end section once again for the same length.
That makes a great and especially quick scarf. And it is a great way to use a new pattern stitch that might drive you nuts for the whole length but will be nice for just those 2 little bits.
My favorite for a scarf of that style that shall go as a quick but effective gift would be:
Either do a cable on garter stitch background of a series of cable crossings then continune in garter. Maybe put a cable pattern in the middle again?
You may want to look into reversible cables to create a nice backside since it will show. That is not hard. Just google a bit.
a cable looks great, too when you cross the ribs of ribbing (not just crossing 2 strands but 3). I may make it to take a picture of the scarf I made for my husband last spring. That is made like that and was just wipped up on a friends shopping receipt one morning 
- [B]a stitch on its own[/B]:
for example raspberry stitch, bamboo stitch and the like. lace… whatever. Just browse for patterns.
Heringbone for men’s scarfs for example (I don’t know who will get the gifts), or that pattern Jan showed in the first link.
Some patterns will look vastly different from the bottom edge then from the top. If you chose a pattern like that, then it is smart to make 2 pieces, each beginning with the pattern section and running to the middle of the scarf - don’t cast off. Then use kitchener stitch to connect them. No one will ever see that!
if you do a lace edge (one that creates a wavy border) and just continue straight, that is quick and very girly if you let it 
- [B]stripes the “other way”[/B]
A funny self knit scarf has stripes running the length of the scarf.
Just cast on as many stitches as you need for the length of the scarf (yes, that is a lot of stitches).
knit in plain garter stitch, that is enough for this.
change color randomly, maybe use one self striping yarn together with other solid color yarns… and so on. just knit about 5 to 6 inches up. And there is your scarf.
Don’t fear the project: the amount of stitches is the same a knitting the short rows!
-[B] a neckwarmer: [/B]
not every scarf needs to be long. Check into neck warmers.
all scarfs can be decorated with beads, tassels, pompons and the like. That will make the patterns look very different, too.
I guess, you make the scarfs for people that partially or all know each other. So it might be good if they were very different to show off a rainbow of knitting skills instead of just a mind set of endurance.
the good thing with all this, too, is: any yarn with matching needles will do.
I guess, that is more ideas than scarfs I ever made myself. But you should find 12 ambitious projects to make until x-mas.
Let us see your progress, will you? I would like to know which ones you do.
If you want more inspiration: www.garnstudio.com has a bunch in “Accessory” - they are all for free and well explained.