Ars Technica has an in-depth article explaining the various clues, puzzles, and Fringe Easter Eggs that are hidden throughout Fringe. Of course, FringeTelevision.com is mentioned as the comprehensive place to follow all the clues in the show.

Erica Sadun's article mentions The Observer appearances, Next Episode clues, and also takes a crack at decyphering the mysterious Fringe symbols or "glyphs", but it looks like this Fringe puzzle may be the Kryptos of Fringe clues.

If you'd like to take a whack at it yourself, Fringepedia has a compilation of all the glyphs shown during the commercial breaks.