The British Library has a really incredible resource: a map of the United Kingdom that you can click on to hear the accents in different regions. It’s really remarkable how different they are, even within the same city! This means that many of the recordings are quite difficult to understand, but sometimes transcripts are provided.
Elllo.org has a searchable database of hundreds of interviews with native and non-native English speakers from around the world with a short comprehension quiz at the end. Use the search box to find something that’s interesting to you! Some of the interviews have transcripts and some don’t.
English Club has lots of information, quizzes and guides to help you understand and practice English better. Their forums are a great place to chat with other learners about things that interest you.
The English Blog is a great place to browse lots of news stories and videos with notes from an English teacher. He updates the site daily with relevant stories and interesting cartoons and videos that show real English in context. There really is a huge amount of material here (search the categories) as well as a lot of links to webistes for English Language Learners (ELL) and podcasts.
Using English is particularly useful for its phrasal verb dictionary, idioms dictionary and ask a teacher forum. They have quizzes about phrasal verbs and if you have any questions they have special forums for phrasal verbs and idioms. If you’ve heard an expression in a film or read something in a book that you just can’t understand, ask the helpful people at Using English. I post there sometimes, too!