This free app is a enables children to use their finger instead of a pencil to trace block letters in upper and lower case for beginner handwriting practice.

The Letter Fromation section of this Phonogram Page provides brief videos showing children how to block print their lower case letters. 

Handwriting For Kids has manuscript (block lettering) and cursive practice worksheets for letters, words and sentences. Worksheets are available for right-handed and left-handed writers.

There are articles and advice for teaching handwriting, penmanship and helping learning disabled students improve their handwriting.  There are a few worksheets available in Spanish.

You can customize some worksheets to include pictures, including pictures of American Sign Language signs for the alphabet.

Be sure to check out the animations for writing cursive lower case letters.

Use this interactive site to generate a custom-made worksheet to help students practice handwriting in D’Nealian or Zaner-Bloser, in cursive or manuscript styles.  There is also a library of more than 23,000 worksheets others have created that you can print.

From site: 

Create your own custom handwriting worksheets for handwriting practice! You can choose traditional or modern print styles.