http://garywillis.com/pages/lessons/read.html
I'm actually surprised no one has suggested this. The best method I found was to separate the two aspects that vital of music reading, those being the notes themselves and the rhythm. Take the Gary Willis thing for notes and something else for rhythms. It's best to work incrementally on it and to keep going by upping the tempo a little bit each time. I used to play a game with myself that if I could sight-read the notes perfectly on 3 generations in a row, then upping the tempo by 2bpm. I got so chuffed with this that at one point, I'd treat myself if I nailed it 10 times in a row. Lots of curry was consumed in my note-reading progress, naturally.
Another note to throw in on this is to go with "ACEG" in between the spaces on the stave, so if you lose your cool and your mind at the same time, you've got a partial mental safety net to fall back on. Just remember it's not a race and you're welcome to PM me if you like!