Supporting Students with Mathematical Models from Eureka Math: A great overview of how related models are used to reach all students as well as links to model specific resources (i.e. number bonds, tape diagrams and area models).
This is a collection of virtual math manipulatives from other sites all organized and in one place.
Note: Some Braining Camp manipulatives require payment. There is usually a 30-day free trial if you want to try them out first.