Here's a website to help real-life neighbours, not just in the same building but in the neighbourhood, to be able to find each other for help, locally. In particular, for borrowing and lending goods.
At this site, one can order a batch of pictogramme stickers, and stick those on one's letterbox which mean "I've got this item, and am willing to lend it to you or else to help you use it." http://www.pumpipumpe.ch/that-is-how-it-works/
Seems like a fine idea to me.
At a party last year, I met a woman who lives an an area of Bern (don't know which) where, she told me, this is now working very well. Whenever she and her family need some equipment she doesn't own, they take a stroll around the streets nearby, peering at letterboxes, till they find the corresponding sticker, and then they ring the doorbell or leave a note in the letterbox, asking the potential lender to phone them. Similarly, she receives such enquires for things with which she is willing to help out.
This is not imposing or intruding since, by having stuck the sticker on his/her letterbox, the potential lender has already indicated his/her willingness to help out.
Does anyone have experience with this system?