Using the service:
- Register
- Browse categories: All categories | Categories that currently have items listed
- Search for items: Basic search | Advanced search
- Search profiles (your saved searches): Add | View
- Offer to donate an item
- Manage your items (update, cancel or suspend an item; manage pictures)
- Change your password or personal information
- Contact webmaster (privately)

References:
- USPS postage calculator
- How donating for a tax deduction works
- Shipping policies: USPS - UPS - FedEx
- How to Verify the Exempt Status of Public Charities
- IRS Publication 78 - Cumulative List of Organizations (registered as charities and non-profits)