1. A computer-implemented method for generating personalized trending topics, comprising: using a processor device, performing 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 given user; receiving an in-stream feed of second trending topics based on the user's recent on-line activity including 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.