1. Elf Yourself - Yes, I do this every year, and it never gets old. Here's the 2014 Joiner family edition for your viewing pleasure.
2. Reindeer Cam - In case you haven't been introduced to this
3. Google Santa Tracker - Phone Call from Santa - This allows you to have Santa make a personalized phone call to people! It prompts you to enter a variety of information, like the person's name and location, but it also lets you throw in some important details, like what kind of food Santa should request they leave on Christmas Eve. Choices include chicken and waffles, two chicken tacos, and more!
This would be great for those of you with kids old enough to actually listen to a phone call, but we mainly used it to prank our adult family members.
4. Google Santa Tracker - As the name suggests, this allows you to track Santa on his journey around the world on Christmas Eve. We obviously haven't been able to use this yet this year, but will definitely be watching Santa's progress the day after tomorrow. (Oh, and if you go now, there are other activities in Santa's "village" to tide you over, including the phone call option.)
5. Video Message from Santa - My friend, Heather, told me about this gem and it did not disappoint. Similar to #3 above, it allows you to input specific information about the recipient, and even lets you upload a picture of the him/her. We created one for Colby and Clara and they were glued to the screen: