APWU.org and PostalReporter.com are the best resource websites for Postal workers.

In addition to constant updates of Postal news, both sites have dedicated resource links for the following issues:

FMLA 

Retirement [regular and disability]

Veteran rights

Light/Limited duty

Reasonable Accommodation

This site has multiple links related to information and benefits for Postal employees.

PostalReporter.com
National APWU website
PostalEase
21st Century Postal Workers

LiteBlue
e-Reassign
Thrift Savings Plan
OWCP homepage
Department of Labor
Office of Personnel Management
Federal Times
Neighborhood Federal Credit Union
United States Postal Service