Google Reader's "sort by magic" (under "View settings") might work for you:

""" A third option, Sort by magic will rank items by "magic." Personalized magic ranking is automatically generated, taking into account your past reading behavior (including liking and starring) and global signals. We'll do our best to display items in the most relevant and interesting order -- click the Like button on things you think are important or enjoy reading, and we'll learn to put items like that first. """

http://www.google.com/support/reader/bin/answer.py?hl=en&...