12. An information processing system for generating personalized trending topics comprises: a processor device; and a memory operably coupled with the processor device, said memory comprising computer-executable instructions causing a computer to perform steps of: for a given user, producing a social timeline by logging content posted on the given user's accounts on social media sites; analyzing the social timeline for recently posted content to derive an interim summary of first trending topics for the user; receiving an in-stream feed of second trending topics based on the user's recent on-line activity such as page views, queries, and clicks; augmenting the social timeline with the second trending topics from the in-stream feed to produce an interim list of third trending topics; ranking the third trending topics by source category using a frequency index; selecting a subset of highest ranked third trending topics from each source category; and presenting a personalized trends module comprising positions allocated to the subset of the highest ranked third trending topics.
13. The information processing system of claim 12 wherein the computer-executable instructions further comprise instructions for: ranking the source categories by the frequency index; wherein the source categories comprise social media and on-line activity; and wherein selecting the subset of the highest ranked third trending topics comprises weighting the selection proportionately to the ranking of the source categories, such that the source category with more occurrences in the timeline is allocated more positions in the personalized topics module than a source category with fewer occurrences in the timeline.