Not a website as such but have a look at
www.digiguide.com. It's a sort of PC version of Sky's EPG but fully searchable and covering hundreds of TV and radio channels. Not free but a reasonable £8.99 a year for updates. You can set up favourites and reminders based on programme titles, keywords, etc.
One word of warning though. Digiguide, along with every other TV guide (paper or online) use the listings as provided by the TV stations, which are often very vague. Typically Sky will bill a show as "high speed action from around the circuits" without saying specifically what races and where from.