(inspired by and based on a response from Fabien today on the Community Mailing list)
FOR EVERYONE:
- A lot of documentation at https://www.odoo.com/documentation/user/9.0/
- FREE Odoo v8 training videos and slides: https://www.odoo.com/slides/user-training-4
- FREE Odoo v9 training videos: https://www.odoo.com/slides/odoo-9-training-5
- Documents and posts on many topics (business, competitors, features, etc.): http://odoo.com/slides and https://www.odoo.com/blog
- Videos of major features: https://www.odoo.com/page/tour
- FREE webinars every week.: https://odoo.com/events
- A tour worldwide when launching new features (in >10 cities), e.g.: https://t.co/QZncTlWVUP
- Annual (180 free conferences) during Odoo Experience: https://www.odoo.com/event/420/page/website_event.introduction-odoo-experience-2016
- Visitor Live chat on http://www.odoo.com
FOR DEVELOPERS/ADVANCED USERS:
- A lot of documentation at https://www.odoo.com/documentation
- Dozens of <module_name>/doc/*.rst files, such as: https://github.com/odoo/odoo/blob/9.0/addons/stock/doc/stock.rst
- PR's that Research and Development are working on (a peek into what's coming): https://github.com/odoo/odoo/pulls?q=is%3Aopen+is%3Apr+label%3ARD
- Great community tools: mailing lists: https://www.odoo.com/page/odoo-community, forum: https://www.odoo.com/forum/help-1, transifex: https://www.transifex.com/odoo/odoo-9/, ...
- A new API at version 8 to ease developer on boarding and improve their development experience: https://www.odoo.com/documentation/8.0/reference/orm.html
- Ability to test stable branches, nightly branches, and development branches (for next versions and new features in progress) directly in Odoo's continuous testing environment Runbot: http://runbot.odoo.com/runbot
