iTunes Widget Builder: Use the iTunes widget builder to display a list of apps, books, or podcasts from the App Store, iBookstore, and iTunes. Widget Builder will give you HTML code to place on your site that displays the icon or artwork for each item you've included. Read my post for more about iTunes Widget Builder.
Edshelf: Teachers can put apps and websites into online collections. Edshelf provides a widget for each collection of resources.
List.ly: Enter web links into a list and embed. Free accounts are limited to 10 items in a list.
TES Teach with Blendspace: Gather a set of resources and put them into a widget with Blendspace. Those resources can be any combination of web links, online videos, documents, and text. Each item is numbered and is automatically given a thumbnail preview image. You will need to copy a public lesson to your account before you can share as an embedded widget.