That said, here are some examples from airports I've recently been in.
DFW - horrible contrast (white letters on beige background). Fairly easy to follow, though.
DEN - Good contrast, signs well spaced. Arrows difficult to follow, especially near escalators.
FLL - Video paging boards difficult to read, especially if you are in a big crowd. Otherwise very good.
LAS - Excellent signage, except the signs are overwhelmed by the openness of the main terminal.
LAX - Could benefit from some more signage, but not bad.
PNS - good contrast, but the arrows are hard to follow (shaft of arrow too wide). Easy to follow, but it is a small airport so they don't need much.
DCA - Font too small, and lighting is uneven making them difficult to read.
I'd love to hear your comments about signage at other airports