Teachit is the mainstay of English teachers in the UK, and for good reason. This site contains thousands of multimedia resources including 'Whizzy Things' that you can use on your IWB. Covering a whole range of topics related to Literature, Language & Media, files can be downloaded in pdf format. A subscription allows downloads of customisable Word documents, but if you contribute a small number of acceptable resources, you can get access for free. They also own the late Andrew Moore's site which is excellent for learners to access very comprehensive notes on a range of texts and topics.
[For teachers outside the UK, Key Stage 3 (KS3) covers ages 12-14, KS 4 covers 15-16 and KS5 is 17-18 (pre-university courses).