You can find personalized Christmas decorations at several websites. Squiddo.com has a variety of Halloween themed Christmas decorations for you "dark tree". Or, you can try searching for ideas to create your own homemade decorations.
You can find shatterproof plastic Christmas decorations from here: (http://www.displayit-info.com/christmas/trim_orn.html). They are very colorful Christmas ornaments for your tree.
You can find unique Christmas decorations and ornaments at http://www.squidoo.com/christmas-tree-themes. There are also gothic Christmas trees and decorations. Try http://www.squidoo.com/GothicChristmas
Unique and unusual Christmas decorations can be a lot of fun. You can find some examples at http://www.toxel.com/inspiration/2010/12/25/unusual-christmas-decorations/, and http://www.squidoo.com/christmas-tree-themes.
There aren't that many scary decorations and they seem to be limited to ornaments. Try http://weburbanist.com/2008/12/19/strange-bizarre-geek-christmas-tree-ornaments/. You can also find skulls decorated with Christmas decorations at http://www.squidoo.com/creepy-christmas-decorations
The Christmas Tree shop offers Christmas decorations year-round at very reasonable prices. Seasonally, you can find some great lighted decorations at places like Target and Walmart.
You can find origami Chrisrmas decorations. You can find origami Christmas decorations at www.origami-resource-center.com/christmas-ornaments.html. These Christmas decorations are not too hard to make.
I would recommend looking at amazon.com or Ebay.com for some great Christmas tree decorations. They offer an incredible variety so that you can have a theme for your holiday decorations as well as being very affordable.
My favorite place to find modern Christmas decorations is Target. Their decorations suit the modern style. You can also find decorations from Martha Stewart at Kmart.
If you are looking for Christmas tree decorations then nearly every supermarket and department store will stock them in the lead up to Christmas. You can also get them online at Amazon and Ebay.
You can find a good deal of outside Christmas decorations. You can find outside Christmas decorations for a good price at www.amzon.com, www.overstock.com, Walmart, and Target.
There are many places where someone can find information about Christmas light decorations. Websites such as, Christmas Central, and Home Depot both have information about Christmas light decorations.