There are some successful and well established forums that cover the Atari Lynx in detail. Whether you are new to the Lynx and have some questions, or are into developing your own homebrew game, or just want to show off your collection, these are a great places to find a dedicated community and are a fantastic source of information.
Here's a list of the best Atari Lynx discussion forums that you can join -
Atari Lynx Programming
Atari Lynx High Score Club
Atari Lynx General
Atari Lynx Games
Atari Lynx Development
Atari Lynx Help
If you know of any other forums please get in contact and let me know.