If you right click the cross on your map, you'll get a small pop-up menu with options to rename the marker, delete it, paste it into your Memo Pad or chat window again. Note: "Delete All" will delete all markers on every zone map, not just the one you're viewing. The marked locations will persist should you log off.
Note: I tried this before and it worked, but in the OB now it did not. so either its a bug or the map marks only persist a short amount of time. To be save, copy them over to your Memo Pad.
The build in Memo Pad (Menu -> Community -> Memo Pad) allows you to store any notes or links you might want to remember ingame. If you intend to store a link, right-click it in the chat window and you'll get the option to save it into your Memo Pad. To paste a link from your Memo Pad back into the chat window use ctrl + right-click on that link.
Another great idea: Use the Memo Pad to store Rift Locations. Just copy this code (found it posted by tpg0007, but updated the zone names) into your Memo Pad and use it as a reference.
Other links you can create to store them:
# Link to item information in chat by ctrl + right-clicking the item.
# Link to quest information in chat by ctrl + right-clicking the quest title in the Quest Log.