Google Maps today, launched the "+1 button for custom maps", now, by just clicking the +1 button you can tell other viewers that a particular map is helpful. You can find the +1 button underneath the map description on public maps when you're signed into to your Google account.
Google also allows you to keep track of your +1'd maps by going to your Google+ profile, and clicking the +1 tab. Your +1's are always public, but your +1's tab doesn't have to be. You can choose to show this tab to the world, or simply use it to manage your record of things you love around the web, informs Google.
Currently, the +1 button only shows up on maps.google.com and not on embedded views of maps.
You can also create your own custom maps and share your must-stop-spots for travel destinations or your own neighborhood. To get the link for your map, open the map and then click the link button in the upper right. Copy and paste this link into an email or IM or post it to your Google+ profile so others can find it, explains Goolge.