The Bill Leavitt series...
'Multiple position reading studies' books 1 and 2, covers all position up to 12th and multi-position studies too.
'Reading Melodic Rhythms' - a great book, lots of fun in this one.
'Reading Contemporary Guitar Rhythms' - M. T. Syzmack - A similar format to 'Reading Melodic..' but also has rhythm guitar duets to do with another guitarist.
'Melodic Studies and composition for guitar' - Fred Hamilton. A different take on things, more in line with Goodricks 'unitar' theory. Has some odd meter studies in too.
I used the Charlie Parker Omnibook a lot too, but the thing that made the biggest difference to my reading was getting together with a sax player and sight reading the real books together (it threw up the odd bad transposition between the C and Bb books too, some real stinkers in there ; )).
Theres also http://www.practicesightreading.com/ (which others have posted on here before) for rhythms.
I always tend to go through phases of practising reading a bit everyday (20 mins) but then slacking off, its usually at that point I get booked for a roasting sight reading gig and the process begins all over again.