I entered Bloglines and set up an account, which was really easy.
They listed information categories and requested preferences. I chose only from the left column and indicated books and science.
I checked each of the categories that I had chosen and the 1 category that was chosen for me. I then proceeded to edit the ones that I didn't feel were really beneficial, including the one the site chose for me.
Now I have a reasonable 3 categories. However, this may prove to be far too many categories to "keep on top of", so I may be revising in the near future.