Since we live in Maryland we found the Maryland State Energy Administration to be helpful with a grant for our geothermal installation. They worked with us get our paperwork in for the geothermal Maryland grant (actually its called the Clean Energy Grant) which helped offset some of our costs. They have both residential and commercial grants.
A big word of caution for geothermal in Maryland (and probably anywhere else) - make sure you check in with your locality and find out if there are any pending grant programs. We missed out on some money since the grant came out after we installed our geothermal system. Since our system was already installed we wern't looking when Montgomery County, Maryland passed a bill offering grant funds that we were eligible to receive. We found out after the deadline for our grant application passed and Montgomery County refused to allow us an extension.
The school where I taught in Montgomery Country, Maryland, Gaithersburg High School is getting a new school facility to be heated and cooled with geothermal. In addition to GHS going with geothermal, Maryland has a number of other schools already using geothermal (e.g. Richard Montgomery HS).