Here is a way to create Content Aggregator-
1) Create a Google Alert for keywords (like say MapReduce and Hadoop)
2) Create a WordPress.com free blog and enable the Auto Post by Email Feature (using manage my blogs in Settings- Reading in Left Bottom Margin). This creates an email with random numbers that can enable you for sending emails and thus auto posting.
3) Create an Email Filter in your Gmail Account to auto forward this to the post by Email Account
Note you can thus create an auto aggregator and pick and choose for creating a Keyword specific or domain specific newsletter. It is all free and takes 15 minutes to set up, and is then automated.