ShortScale.org

I'm looking to take it to the next level again and I'd like to learn a bit more theory.

Anyone got any recommendations?

Depends how advanced you'd like to go. I've found Guthrie Govan's creative guitar books very useful, as is learning from the abrsm theory grades. Possibly the most useful for myself though has been Mark Levine's Jazz Theory book.

Check out some of the tutorials on www.jazzguitar.be there are some great lessons on theory, don't worry about the fact its jazz all the theory is applicable to every genre of music.