Below a summary of the free items to be found in The Sims 3 Store. It is advised to download free items right away cause some items may be removed at some point.
*No longer available in the Store. Will remove it by EA's request.
**Part of a different free Christmas set.
Some people say that if you're registered with EA, you will get an e-mail on your birthday with a link to a free pack. Read all about it here: Sims3Forumpost.
However, many simmers say they didn't recieve anything on their birthday so it is unclear if this pack is still being sent out or if it's only available for certain regions.