(In my house they are anyway)
Meringues are always good and simple to make. They can be coloured and sprinkled with all manner of fancy bits.
Pretzels are also good but do require a bit more work. Christmas is also the time for making those rich fudge cookies, slabs of sticky toffee and smooth, creamy chocolates.
Gingerbread figures and rings are also nice to see. But the main plus-points with edible decorations is that they do not require storing until next year, do not get broken due to bad storage and help to keep any visiting children quiet if only for a short while!
And with a little more work and some pretty packaging they can serve as relatively cheap presents that always go down well!
There are already some scattered about on this site but, as the saying goes, the more the merrier!