When I’m watching currently-airing series, I assign each episode its own rating. This was something I started mainly for making pretty graphs, and as such the average rating of a show’s episodes may not be the same as the rating I ultimately give it. When I rate each episode, I also put that data into a big spreadsheet, which in turn pumps out a nice picture of the running average rating for each series after each episode. Until I can find a suitable way to update it automatically, I’ll try to get a new version up at least once a week.
The spreadsheet also gives me a graph of the raw rating data, which I won’t bother to post unless people really want it, as it is moderately unintelligible.