We are humans and we like to go to different places. There are times when we need to make our location known (voluntarily), to friends, relatives or partners for meeting them at a specific place, for assistance when we have a problem or fun when we find a special beach, shop, event, etc.
Just send a message to them and, provided they use the WAMII app too in iOS, they can find you on the map and join you. Also, you may "mark" your current position when you find a place you want to visit at a later time or leave your car or anything else you need to pick up or do at a later time. The uses are just too many to list.
This service uses Apple's Maps native application so it complies to relevant country / territory limitations.