L E Modesitt Jr
There is an old thread floating around (see above)
I've read an awful lot of his works and really enjoyed the Recluse saga. Every time another book comes out I start thinking that he is over stretching the ideas, but then start reading and away we go again!
I really enjoyed the first three books of his spell singer saga, and have read some of his SF which is not quite as enjoyable but still fun.
However his Tangable Ghost books are magnificent, an alternative reality where ghosts exist.