A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate in the Unity community.
Separate names with a comma.
Check this video out for some ideas: http://www.youtube.com/watch?v=y7QSwaCIbR8&context=C280bfADOEgsToPDskLNa_Oc93s-VhKkoX1lvYRZ