Jerry Selin

This plugin is best fitted for not so precise people. When products are sold mostly with one piece per order, it is easy to overlook multi-quantity orders. This plugin will highlight the background of the quantity cell if the quantity is over one.

Highlight Multiple Quantities In Order

Works great

Highlight Multiple Quantities In Order makes important highlight on order if customer have ordered over one quantity of a single product.

B Hays

Limit the display of product fields with Gravity Forms based on the number of entries.
Currently only works for single product fields with a quantity defined. Limit does not count against entries in the trash.
Great for event registration or product quantity limiting.
Built with Better Inventory with Gravity Forms from Gravity Wiz 
http://gravitywiz.com/better-inventory-with-gravity-forms/

Gravity Forms Quantity Limiter

Limit the display of product fields with Gravity Forms based on the number of entries.

Highlight Multiple Quantities In Order vs Gravity Forms Quantity Limiter