Pokestops are, in general, "street furniture".  While most of these were initially Ingress sites, and many others have been added (notably Starbucks and Sprint stores):

Churches, temples (many faiths), zen centers.  I no longer live near a Sikh house of assembly, nor a mosque, so I don't know about coverage of all faiths.

Clocks.

Fountains.

Architectural details (gargoyles, mosaics, art deco