I joined almost 5 years ago, shortly after a VERY fast decision to ER at age 61 (one week from deciding my BS bucket was full to my last day in the office, after years of saving, managing investments and making projections).
It was wonderful to encounter so many people with similar mindsets- LBYM, there's life beyond work, "millionaire" is not a pejorative, etc.
Some of the things I've learned (can't possibly list them all):
-Money-saving ideas: hearing aids at Costco, Ting for cellular, Requestatest.com for routine medical tests, etc.
-Navigating Medicare: traditional Medicare vs. Advantage, claim issues
-Travel ideas
-YTD Investment performance- good to let me know how I'm doing compared to others with similar investment mix
-That there are many kinds of ER- everything from bare-bones, use the public library and free entertainment and minimal frills such as restaurants to "blow that dough" mode.
-The availability of HSAs within Fidelity. Opened one, rolled over balance from previous provider, investment results MUCH better!
I hope I've been able to contribute wisdom of my own in some of these areas!