This Word Document contains particulate models of ions, including charges. Some of the ions include: oxide, the halides, sulfate, sulfite, nitrate, nitrite, phosphate, hydroxide, and many others.
I cut these ions out and have students model various ionic compounds, then name and write the formulas. The particulate models of the polyatomic ions really help students to see that these are bound atoms that act as a unit and carry the charge.
*Note: The ion models are NOT to size - most of the metal cations are all the same size circles.