Benefits available to Debian Developers and Debian Maintainers are documented in the Developers Reference:

https://www.debian.org/doc/manuals/developers-reference/resources.html#developer-misc

In addition:

Certificates

DDs can get certification of their membership (586186).

LWN

DMs can get gratis LWN subscriptions the same as DDs (581603)

Steam

DDs and DMs can get gratis subscriptions to Steam (736381)

Gandi
Gandi (www.gandi.net) provides website hosting, cloud computing, domain registration and X.509 certificate services.

Email non-profit@gandi.net from your @debian.org address providing your Gandi handle.