It's possible to find a number of samples by doing an internet search. Please note, the three policies that are referred to on the IRS Form 990 (Part VI, Section B) are Conflict of Interest, Document Retention and Destruction, and Whistleblower Protection.
Here are some resources that we have found:
Board Source sells The Nonprofit Policy Sampler which includes a large number of sample policies and other sample documents. It is a book with CD.
Charities Review Council has a number of sample documents and policies, including:
Conflict of Interest Policy
Discontinue Contact Policy
Document Retention Policy
Travel Expense Policy
Record Retention and Destruction Policy
For a discussion of things to consider, go to National Council of Nonprofits
Blue Avocado model
Authenticity Consulting sample
For Donors Forum sample, go to www.donorsforum.org and search Record Retention
Code of Conduct
Volunteer Power sample