Shortening of 'seamed stockings', vintage or reproduction nylon or sometimes silk hosiery with a seam going up the back of the leg from under the toes to the stocking top, or welt. The stockings should be shaped to the leg (fully-fashioned) and are sewn up the back, hence the seam. Modern seams are often purely aesthetic and are not neccessary to the construction of the stocking.
Phwoar! Look at that wiggle! She looks good in that tight skirt with seams 'n' heels.
Strips of newer, smoother concrete on a pavement that has undergone reconstruction at some point. Usually a seam runs along the pavement and is a different colour or type on concrete. Usually seen on UK pavements.
The seam is smoother than the pavement, lets skate on that for more comfort. The pavement sucks but seam is smooth.