Here are some links that may be of interest:
GREEN ROOFS
www.goodegreennyc.com (green roof design and installation; the builders of Eagle Street)
NEW YORK CITY ROOF TOP FARMS
www.rooftopfarms.org (6000 sq ft. roof top farm in Greenpoint, Brooklyn)
www.gothamgreens.com (a 15,000 sq. ft. hydroponic garden from the visionaries who brought us the Science Barge)
SEEDS
www.rareseeds.com (Baker Creek Heirloom Seeds, the source of several vegetables at Battery Rooftop Garden)
www.johnnyseeds.com (Johnny’s Seed, headquartered in Maine. Next year we hope to try their ‘Geneva PMR’ Squash, the first ‘Waltham Butternut’-type squash with high resistance to powdery mildew.)
www.highmowingseeds.com (High Mowing Organic is known for high-quality organic seeds for varieties selected for good performance in organic conditions. More than 450 heirloom varieties available.)
URBAN FARMING GENERALLY
www.thecitygreens.com (local food stories, see especially the 3/17/10 blog for a round-up of roof top farms in NYC; interesting but incomplete)
www.ediblebrooklyn.com and www.ediblemanhattan.com (frequent updates, all things local food in NYC)
VEGETABLE VARIETIES
http://vegvariety.cce.cornell.edu/index.php (fantastic site that assists in determining which varieties have been most successful in your area)
SCHOLARSHIP ABOUT LANDSCAPE AND PLACE
http://foundationforlandscapestudies.org (site of the Foundation that publishes the periodical Site/Lines, gives awards and subventions for books in the field of garden and landscape studies, and whose mission is to foster an active understanding of the importance of place in human life)
Battery Rooftop Garden Blog 