I love it when I come across a residential street and every house has contributed to the nature strip or pathway in some horticultural way. The whole street sings, and you get the feeling that the people living there are happy (and getting on!). A notable example is Ada Place, Ultimo, where each terrace must place at least a couple of interesting pots on their tiny roadside front porches. I'll snap a pic next time I'm there. Where else have you seen this?
Above are some heftier citizen-driven (or guerilla) gardens in: Redfern; Thomson St, Darlinghurst & Flanagan Lane, Melbourne. HF.