- Off Track Betting, Ronkonkoma
- Office Supplies, Equipment & Office Furniture Stores, Ronkonkoma
- Oil & Gas Exploration & Development, Ronkonkoma - Oil Field Exploration, Monitoring & Remediation
- Oil Burners Services, Ronkonkoma
- Oil Change & Lubrication, Ronkonkoma - Auto Oil & Quick Lube
- Oil Industry & Oil Field Equipment & Services, Ronkonkoma - Oil Companies
- Ophthalmic Goods, Ronkonkoma
- Ophthalmologists, Ronkonkoma - Eye Doctors, Physicians & Surgeons (Ophthalmology)
- Optical Goods Manufacturers, Ronkonkoma
- Optical Stores - Eyeglasses, Lenses & Sunglasses, Ronkonkoma
- Opticians, Ronkonkoma
- Optometrists, Ronkonkoma - Eye Doctors, Physicians & Surgeons (Optometry)
- Orchestras, Symphonies & Bands, Ronkonkoma
- Oriental Goods & Products Stores, Ronkonkoma
|
- Oriental Restaurants, Ronkonkoma
- Ornamental Nursery, Ronkonkoma
- Ornamental Nursery Services, Ronkonkoma
- Orthodontist, Ronkonkoma - Teeth Straightening, Invisalign & Dental Braces
- Orthopedists, Ronkonkoma - Orthopedic Surgery Doctors, Physicians & Surgeons
- Other Building Materials & Supplies, Ronkonkoma
- Other Electrical Products, Ronkonkoma
- Outdoor & Lawn & Garden Equipment Repair & Service, Ronkonkoma
- Outdoor Equipment & Accessories, Ronkonkoma
- Outdoor Furniture & Patio Furniture, Ronkonkoma - Garden Furniture Stores
- Ownership Organizations, Ronkonkoma
- Oxygen & Respiratory Equipment & Supplies, Ronkonkoma - Oxygen Concentrator, Tank, Machine, etc
- Ozone Equipment, Ronkonkoma
|