December 23rd: Web tool. It came into your work flow this year and now you couldn't live without it. It has simplified or improved your online experience.
I've already told you about my love for Lijit here.
Another great online tool is Hootsuite. It allows you to schedule tweets, which is really helpful when you manage a corporate Twitter account, or have a post scheduled to go live over the holidays and want to send out a message when it's published... hypothetically...
Finally, I LOVE Picnik. This is the site that I use to take my pictures from "okay" and "normal" to OH EM GEE THAT IS AWESOME, like this one:

(I'm going with just the right amount of awesome...)