Use it however you can! Some people say the pine needles will acidify, other say unless constantly used, it won't change the ph much wherever you use it. Best bet: use it around acid loving plants.

If you have a chipper, there you go, got some mulch or compost fodder (I'd mulch if it were me, save it up for spring mulching).

I know some places have "bring your tree, we'll chip it and give you your mulch for cheap," like Chicago.

When I used to have real trees, I'd drop them off at the local forest preserve drop off site, where they...you guessed it...chipped them up and spread them around for mulch.

So...either yet yourself a chipper, find out what programs your city has, find out what local forest preserves may have, or lastly you could try out "hugelkultur" (see useful link).

Here is a link that might be useful: hugelkultur

The leavings of that Christmas tree will not adversly affect either your soil or your compost pile, although piling the cut down branches on top of the compost could slow down thawing if the pile is frozen. There is a lot of research out there that shows that pine needles and oak leaves do not change soil pH in any significant amount with none that shows they will. All there is that these materials change soil pH is folk lore, myths.
We have cut the branches to use as mulch, we have left the tree whole and loaded it with stuff to feed birds and then cut it for mulch.

The whole christmas tree branches that I have tossed into my compost pile, take forever to break down.. so if you can break them up, chip or shred them - that would be best.

I've decided that in addition to a compost pile and mulchwork, every yard needs a brush pile. I'm planning to use the Xmas tree needles in mulch, and the branches and trunk (chopped maybe) in my brush pile.

I guess I'm not as dedicated to green as some of you. It takes a lot of energy (mine & machinery) to chop and chip a spruce and it takes forever for those needles to fall off.

My village collects and chips those discarded trees and allows me to pick up as much hardwood mulch as I could ever want. One trip to the waste yard probably gets me dozens of trees, already ground up.

Neither. Last year's tree is still laying under the evergreens in my bird feeding station, to add extra cover for the birds. And the tree the year before that, was added to a brush pile in the back. This year I'm getting a smaller live tree in a pot that I can plant in the Spring.

Same here, I put it out in the brush pile for the birds. I haven't taken down the morning glory vines on the trellis out back and the birds "shotgunning" out of the vines makes my heart skip a beat or two even tho I expect them.

Do your feathered friends a big "here's to you" by putting the tree out on your lawn after the festivities.
They will use it for landing, resting and feeding if you hang feeders or food such as suet from.

After the needles have dropped and the tree has taken on a not-so-pretty role, then chew it up if you can, chop it up if you can and use the leavings. If not, put it out at the roadside when your community pick-up is slated and let the community compost pile be the recipient.