I know this is a bit of a random question, but after watching a considerable amount of Star Trek, I've never seen a Klingon's foot - only their boots. I know they probably have similar shaped feet to most humanoids, but is there any actually any visual scene containing a Klingon's foot in any series?
Yes, in the episode "Ethics" we see Worf's feet. Whether these are typical or abnormal is never explained but the similarity in shape and size (along with the symmetry of the bump above the fifth digit) would suggest that they are.
This ties in quite nicely with the Klingon anatomical model designed by senior Trek 'Visual Effects Producer' (and Klingon expert) Dan Curry.