21. A non-transitory computer readable storage medium storing one or more programs configured to be executed by a server system, the one or more programs comprising instructions for: receiving a plurality of a particular user's interactions with a plurality of items in a social networking system, each item associated with a category; ranking the items based on the particular user's interactions with the items, each interaction discounted based on a time elapsed since the particular user interacted with an item; for the particular user, ranking the categories based on the rankings of the items within each category; and sending bookmark links grouped by category to the particular user for display, the bookmark links ordered within each category based on the item rankings of the corresponding items within the category, and the categories ordered based on the ranking of the categories.
21. A non-transitory computer readable storage medium storing one or more programs configured to be executed by a server system, the one or more programs comprising instructions for: receiving a plurality of a particular user's interactions with a plurality of items in a social networking system, each item associated with a category; ranking the items based on the particular user's interactions with the items, each interaction discounted based on a time elapsed since the particular user interacted with an item; for the particular user, ranking the categories based on the rankings of the items within each category; and sending bookmark links grouped by category to the particular user for display, the bookmark links ordered within each category based on the item rankings of the corresponding items within the category, and the categories ordered based on the ranking of the categories. 25. The computer readable storage medium of claim 21 , wherein bookmark links are generated periodically for the particular user.