Second idea: garlands. No, not Judy. And not just for the tree - for any empty wall space, boring curtain rod, to hang above doorways, or along the edges of bookshelves.
Take black thread. Buy a package of symetric stickers (colored dots from office supply stores work well). Sandwich the thread between two stickers at regular intervals. Viola'. Cute and funky garland. Use silver or gold thread if you want it to show. Black thread makes the designs look like they're floating if you hang this on the tree or in an open space.
Take coffee filters. The round kind that you can buy 200 for $1 (or so - they're very inexpensive). Get the white ones if you want white, or the unbleached ones for a natural look. As these are for making snowflakes, the unbleached ones may look more polluted than "natural"! Use them to make paper snowflakes by folding them in half a few times and snipping away. The number of sides to your snowflake will depend on how you fold it. Instead of folding in half every time, you can fold in half once and then in thirds. Coffee filters are ideal for this because they are already round and they are made from a thin but sturdy paper that is easy to cut. You can either leave them with the rippled edges (the way the filters come in the package) or you can squirt them with water from a spray bottle and iron them. This is quick and easy to do. (If you don't want white, paint them with dabs of watercolor paints. The filter material soaks the paint up nicely and makes a tie-dye effect.) Weave a string in and out through several and ta-da, another garland.
Take kraft paper. Or paper bags. Or wrapping paper. Cut out a long strip about 4 inches by oh, say 3 feet. Accordion fold this strip every three inches or so. Trace a pattern on the stack of folded paper - a pine tree, a gingerbread boy, a bell - we're using the string of paper dolls idea here, so make sure your design goes off the edges just a little bit on each side. Cut out your shape, but be sure to leave the layers attached on the edges. Open the accordion and there you have it. If you are using plain paper, you can decorate each unit. I started making a string of gingerbread boys last year but ran out of time/energy/creative juice and only got two done. I used shiny dimensional craft paint in those little bottles with the nozzles. It was like decorating real gingerbread with a piping bag of frosting. The string the kids decorated did get finished, but I can't seem to find it : (
Go. Garland something. Watch the Wizard of Oz if it helps get you in the mood, or better yet Meet Me in St. Louis or In the Good Old Summertime (which also stars Van Johnson).
And do check back; I hope to add photos to these posts.
ps Domesticali, if you read this, I've been trying to comment on your blog about maths, but Blogger isn't letting me. I mostly agree with the comments about your son being too young and the teacher not getting it, but I also want to recommend the math program we use since we homeschool. It is called Math U See, and even if you don't use the program, the "how to" is very helpful, and the blocks with their different colors and raised units could be just what you need. They have a free demo DVD.