Celery actually burns more calories to digest than what you eat - it's a "negative calorie" food. Just some random bit of info stuck in my head. Too bad it tastes like crap.
Mish - to start a group, you really just need to make up a simple flyer. There is nothing to "run," really... if it's book, you pick the first title and see who shows up.
If it's about special needs kids or being a sandwich caregiver, you can also pick out a book to go through together (a good one for special education is Negotiating the Special Education Maze), or share some tips (ask the group what topics they think they might want to address - ask the school psych, spec ed coordinator or other service person if they can attend to help the first one). Same thing with elder care - contact the local hospital or nursing home and see if they have a social worker who might want to be a guest speaker.
if it's cooking, pick Italian to start and ask everyone to bring enough for however many people rsvp, along with the same number of recipies to share. If you can swing it, some places have kitchen facilities that you can rent - think the elks club, church, etc., - then you can demo a main dish, too. Some caterers might be interested in coming to do a demo if they can advertise...
Try the garden again - what's the worst that can happen? Do you know how to contact your local cooperative extension? They have master gardeners who have to "pay back" their classes with free advice. You could even think of BECOMING a master gardener, someday, if so inclined.
I'll keep thinking outside the box. That's what pisces/artists do best (just don't ask me to organize anything or do math - I can, but I hate it!)