For several months now, I've been using 'DigiGuide' - and I have to say that it's pretty good. It's a Tv listing piece of software, which allows for flexible alerts (not like the radiotimes system which requires you to find the programme first).
One can set alerts based on actor, title, 'new episode', genre... generally, if you can find something to search on, you can search for it.
Clicking the above link gets to a free trial. I took a free trial and found it to be so useful that I signed up for the software.