I've got some cracks in the sidewalk running up to my house which seem to be getting bigger. They are at the "creases" put in when the sidewalk was layed, but they are as much as 1/2 inch wide and one has a slight change in height which trips up the snow shovel.

Should I fill the space with sand and apply a sealant over them? Should I dig out the sand that's in there and seal them? What kind of sealant? Should I ignore it and hope for the best?