The Foundation Center is a subscription based service, which provides the largest database of information on foundations. Because The Foundation Center populates its database directly from information obtained from IRS 990 forms, it tends to provide less relevant results than a service like GrantStation. One of the most useful options with The Foundation Center, is the ability to do a reverse lookup, whereby you're able to submit a search to see where similar organizations receive their funding. 

The widget, below, will provide you basic information on specific foundations, and allow you access to their 990 IRS forms. For more information, please visit The Foundation Center, at the link to the right of the widget.