Dear Steve. This is a great idea. However, my play group is just a tad slow, so would it be possible to change the nice "Clue" on the back of the card to CLUE in something like size 240, and perhaps in a flouro green colour. Alternatively, what are your thoughts about using a permanent marker and just writing it on players foreheads?
Seriously though I use these myself but nowhere as nicely done as these - great job.
(As a PS I must admit that even with clue cards my players often just don't get it. They are very much bottom of the barrel material).