These are nonprofit organizations who can provide GIS consulting services to land trusts:

• GreenInfo Network (based in California, but works nationally)
  
• EcoTrust (Pacific Northwest)
  
• Alaska Conservation Foundation (Alaska)
  
• SAFC (Southern Appalachian Forest Coalition)
• Conservation Management Institute (Virginia, mid-Atlantic)
  
• Ducks Unlimited (Tennessee, but works nationally)
  
• Northwest Habitat Institute (Pacific Northwest)
  
• Canaan Valley Institute (West Virginia)
  
• North Carolina Coastal Land Trust (North Carolina and Southeastern US)
• Center for Community GIS (based in Maine, but works regionally and internationally)
• BioGeoCreations Private firm, but focuses on supporting non-profits.(formerly of North Carolina, now in New Mexico focusing on West)
• MapTogether - a nonprofit based in the midwest, working there and elsewhere on GIS projects
• Trust for Public Land's GIS group - large national organization has a very active GIS staff who work on a variety of greenprinting and related projects.