TNR-specific resources are here.
Many spay/neuter clinics also offer low cost vaccines,
that list is here.
Below are excellent sources of helpful information about feral cats, fostering, socializing, and more.
Based in DC, Alley Cat Allies is one of the largest cat rescue organizations in the country. Extensive information, tips, and videos.
A directory of low-cost, affordable and free resources for Georgia's pet owners. Calendar of low cost spay/neuter, vaccine, and general pet care clinics throughout the state.
PAWS and WHISKERS is an Atlanta-based rescue organization with lots of information and resources on their web site.
The largest no-kill companion-pet sanctuary in the country, with branches across the country. Lots of general resources and info.
A NYC-based rescue group offering lots of information.