In 1965 Archigram envisioned the Plug-in City. Geoff at Bldgblog describes it:
Archigram proposed using construction cranes as permanent parts of their buildings. The crane could thus lift new modular rooms into place, add whole new floors to the perpetually incomplete structure, and otherwise act as a kind of functional ornament. The crane, "now considered part of the architectural ensemble," Archigram's Mike Webb wrote, would simply be embedded there, "lifting up and moving building components so as to alter the plan configuration, or replacing parts that had work out with a 'better' product."
45 years later, plug-in cities are all the rage in the design pages.
Among its green technologies, The Hive is a water treatment plant and reservoir. The façade is covered with solar panels and wind turbines are located between cells. In addition, each residential unit will have an orchard for local produce.
Because they are independent units in a grid, each unit can have its own roof garden. There is no explanation of how you get to your unit, but it looks interesting. More at Evolo
There is a lot that can be said for plug-in designs. Basic structures last a lot longer than mechanical and electrical systems or finishes, so being able to upgrade units over time makes some sense, plugging them in and out like you would an appliance. It also could let you take your house with you if you have to move.
Brazilian Architect Felipe Campolina's Portable Housing is better resolved, and I think one of the most interesting Evolo entries. It is sort of a vertical trailer park, where you can move your house up and down via a huge elevator. more at "Portable Housing" Is Really A Vertical Trailer Park
I have always loved Andrew Maynard's Corb 2.0, with its travel crane moving units around; More at Andrew Maynard's Corb 2.0: Archigram Reborn
Some commenters thought that Maynard's scheme was derivative of LOT-EK's MDU mobile living unit, but I do not.
Then of course there is Icelandic artist Borkur Eiriksson's dystopian plugin, that doesn't look very green at all.
And my favourite, Theater het Amsterdam's highrise trailer park.