ArcGIS provides several resources including an online version of ArcGIS where you can manipulate layers and access ArcScene. You can also search for map layers and data created by other ArcGIS users.
Here is the link to the online map viewer where you can search for and add layers.
Another useful tool is searching for layers and data to use within ArcGIS.
On the ArcGIS website you can search for data and layers y going to the top right hand corner of the screen and locating the search box.
This is a search for us map. The search results can be found here.
By selecting open you can view the layer in ArcGIS online map viewer.
You can also search within ArcGIS to find layers and data available on ArcGIS online by going to the right hand menu.