Okay, I said I'd do this forever ago, but here are websites and organizations to use to stay up to date on USPS activities. I'll try to add a bit more information later, perhaps a few more organizations.

Just a warning – a lot of this is heavily centered towards businesses, because as much as we mail, we don't touch what they do in one mailing, much less in one year. But for what it's worth, here it is.

USPS Communication

Rate Case Information
Mailer's Companion
Memo to Mailers
MailPro (Replaced Mailer's Companion & Memo to Mailers)
Rapid Information Bulletin Board System


Addressing Standards & Postal Regulations

Postal Explorer
Addressing Standards on Postal Explorer


Non-USPS Resources

Postal Consumer Council (PCC)
Mail Systems Management Association

Thank you Pepper!! Gonna give this a pin-up now!

USPS Index of Countries

Use this link to find M-bag prices, other prices and also restrictions on what you can send to each country (helpful for exchanges).