Enter UrbanGardenShare.org, a just launched community website where you can find just the plot you're looking for with an easy search tool and interface. It's simple: people request garden plots to work, people offer plots. It's like Match.com for frustrated, landless gardeners and the busy homeowners who long for more green. You can browse listings by size or neighborhood, and a short questionnaire allows you to detail your ideal patch of to-be-determined-heaven, time commitment, and gardening experience (You wouldn't want some half-assed buffoon tearing through your backyard beds).
Listings also detail the expected division of labor, from "I want to be involved" to "You're the green thumb, you do it." People offering up garden space can even specify when they'd like said gardening to take place. With waiting lists at P-Patches an arm long in some neighborhoods, Urban Garden Share offers a great communal alternative, and a chance for apartment dwellers to live the dream, even if 50 square feet at a time. It also allows an over eager gardener a built in depository, the garden's owner, for any basil or lettuces run amok.