Linguistic Research Digest. An outstanding blog on predominantly sociolinguistic language issues, written by Jenny Cheshire, Sue Fox and Jenny Amos.
Everything to do with phonetics. An acutely informed blog on the sounds of language, written by John Wells.
How To Say. A knowledgeable guide to the pronunciation of words and names in the news, presently written by Martha Figueroa-Clark, Jo Kim and Marieke Martin of the BBC Pronunciation Unit.