I have two neighbours who I freely borrow from and visa versa. It is a godsend when I'm part way through cooking a meal and realise I haven't got something essential.
We lend and borrow tools, lawnmowers, ingredients, cat food etc..
I lent my tent to one of them in the summer, and when I got a flat tyre she offered me her car to get to work and back (without being asked she just saw me struggling and offered).
We help each other out in lots of ways- of them is absolutely terrified of spiders so I sometimes get an SOS call, the other has a fragile back so sometimes asks for help with lifting and carrying. Both are great cooks and shove soup and cakes at me as a thank you.
They are now great friends and it is lovely to know that there is some support available close by if needed.
Over the years we've provided emergency childcare for each other. When my dad had a heart attack one of them looked after my son several times in 10 days, and when she was unwell her boys stayed with me so she could recover.
I think we all know that it is perfectly acceptable to say no to something if inconvenient. For example, you'd have to prise my last teabag out of my cold dead hand. She was also aware that if she'd trashed my tent I'd have expected it to be replaced, and of course I covered the costs of being put on her car insurance as a fully comp driver.
I feel good when I help them out so it is a win-win situation.