This American Sign Language (ASL) site has signing resources and videos for kids, older students, teachers, and families to help them improve their signing skills.  They include a dictionary, phrase dictionary, and a self-paced series of lessons, among many other learning tools.

With excellent videos, ASLU is a tremendously useful instruction tool. It’s especially helpful for students and teachers who are just beginning to learn to sign. In addition to the videos, there are helpful tips on signing variations and memorizing aids.

From site:  Want to be a part of a popular online community of thousands of deaf and hard of hearing people from around the world? To gain full access you must register for a FREE account. As a registered member you will be able to: Participate in all our topic forums listed below. Post and view pictures. Access to private forums. Communicate privately with other deaf and hard of hearing members. All this and much more is available to you absolutely FREE! Come join us. Hearing people are welcome.

LearningReviews.com note: Topics include education, ADA, and deaf products and assistive technologies.

From site:  DEAF CS is a collection of activities and lessons that use modeling and simulation technologies to help students and their teachers explore math and science concepts. As the deaf students read the material, they can access the concepts in their natural communication mode through authentic ASL, signed by deaf educators and students.