There's rather a lot.
Dresses that are fitted at the waist (e.g. with a belt or waistband) are a stumbling block.
A skirt that is tight around the hips, but loose below the hips, is a stumbling block, regardless of length.
Form-fitting skirts are a stumbling block, regardless of length.
Sparkly, shiny skirts are a stumbling block, regardless of length.
Skirts made out of many layers of semi-transparent material to form an opaque skirt are a stumbling block, regardless of length.
[oddly fashion-conscious in their specificity, ain't they?...]
Seeing a girl's slip through the slit in her skirt is a stumbling block.
The lines of undergarments, visible under clothing, cause guys to stumble.
It is a stumbling block when swimsuit ties stick out from under clothing (e.g. tied around the neck).
V-neck shirts or dresses are a stumbling block, even if they are not revealing.
It is a stumbling block when a girl reaches into her shirt to adjust a bra strap.
Bending over so that cleavage is visible down the front of the shirt or dress is a stumbling block.
Putting lip-gloss on in front of a guy is a stumbling block.
Wearing heavy eye makeup is a stumbling block.
Wearing mascara is not a stumbling block.
Wearing glitter lotion is not a stumbling block.
Playing with hair is not a stumbling block.
Playing with jewelry, such as a necklace, is a stumbling block.
Earrings are never a stumbling block.
...High-heeled shoes (2" or higher) are a stumbling block. [well, yah, especially if you don't know how to walk in them...]
A modestly dressed girl can still be a stumbling block because of her attitude and behavior.
It is a stumbling block for a girl to bend over with her backside towards you.
It is a stumbling block to see a girl lying down, even if she's just hanging out on the floor or on a couch with her friends.
Seeing a girl stretching (e.g. arching the back, reaching the arms back, and sticking out the chest) is a stumbling block.
Lifting a long skirt any higher than the knee in order to step over something is a stumbling block. [in other words, it's okay if YOU trip and fall on your ass...]
Extending the middle finger toward a boy is a stumbling block, regardless of whether the nail is painted. [no, i made that one up]
It goes on. Oh, it does go on.
And, as I said over at Demetria's:
you know, i wonder if anyone ever suggested to the poor lads that the best way to avoid "stumbling blocks" might in that case be to, say, -never leave the house.-
or turn on the TV. hey, idle hands are the Devil's Playground--you know, there must be a -lot- of chores around the house those nice young men could channel all those lusty energies into...