Here are some web sites and documents to help with creating a homework policy.

The Grading System Our Kids Deserve
Grand Island Public School Homework and Reporting Policy, Guidelines, and Practices.
Sample Homework Policy Guidelines.doc This document contain a summary of what should be in a homework policy as well as ideas about parent involvement.
Sample Communicate.pdf This is an article about communicating purpose to parents and students on a daily basis.
Sample Communicate purpose.doc This document provides a sample of a homework form that could be used to communicate to parent and student about the purpose of the homework assignment and receive feedback from parent as well as student.

NEA PTA homework policy.doc Sample Homework policies from National Education Association and National Parent Teacher Association.
sample homework policy.doc A document by Jocelyn A Butler. Two different samples of homework policies are on pages 4-6
Homework policy.pdf This policy contains some pointers for parents

Fifty instead of Zero Misses the Point is a discussion by Cathy Vatterrott. She proposes ZAP "Zeros Aren't Permitted"
Teaching Heroes, Toss the Zeros is the article referenced by Cathy in the discussion above. A policy to deal with incomplete homework is explained.
Students desire input into homework policy. In this article students look for relevant assignments for which they are provided feedback as a part of a new homework policy.

Surveys from Cathy Vatterott
parent hw surveyshort.doc Parent survey
student hw survey long.doc Student survey
Teacher hw survey.doc Teacher survey

Norris Middle School has a grading policy that includes homework expectations and grading of homework. Located on the left side under homework policy.
The Nebraska Parental Information and Resource Center has two sample homework policies available.
From NCTM, answers to parents when they ask for advice when helping with their child's mathematics schoolwork.