History - look out for podcasts on iTunes, I forget the name but type in GCSE History and a good set by a history teacher will come up. And Bitesize is very in-depth.
French - Languages Online.
German - Ditto. And for good listening practise and even vocab, I recommend downloading Schaflos in Munchen/anything from RTL and just trying to pick out words, from iTunes podcasts.
English - nothing beats just picking up a book and writing about it. And just writing articles and stories within a set time limit.
Physics/Biology/Chemistry/Maths - SAMLearning.