Playing with feeling is like having a conversation with someone... you can learn new words, maybe some ice breakers, but no one can really teach you how to hold a conversation with another person. Guitar really is like talking... there are two main aspects to talking - pitch and inflection (people shape their mouth to create certain syllables, and most people raise pitch near the end of sentences for questions, for example). The same goes for guitar playing, you can vary your pitch and inflection. No one can tell you how, it just comes from doing it over and over and over.

Toolfreak has a good idea. When I hit the old writers block, I sometimes just randomly tune my guitar and place my fingers randomly. When I hit a cool sound, I figure out the notes and write them down. Then I learn how to play the chord in standard tuning. Another thing I do is randomly tune my guitar then improvise over a jam track. This way, you can't use familiar patterns and it forces you to use your ear and do new things.