USA Carry Interactive Reciprocity Map - A good map that takes RESIDENCY into consideration.
Handgunlaw.us Maps and State Information - A great resource for information and maps on other states when traveling. Note their maps do NOT consider residency.
Illinois State Police Firearm Safety Bureau - CCW and FOID applications online
ISP Person-to-Person Transfer Page - Check a buyers FOID status and get an approval code before non-FFL transfers
Revoked Illinios Instructors - the wall of shame
4 Permit Recognition Example (Illinois Resident, Utah, Arizona, Florida.) Map via USAcarry.com