OmniNav - The Virtual Tour Guide
- Download an audio tour of top DC sights (MP3 file format) Subscription required.
- http://www.omninav.com/Main/omninavdc.php

Natalie Zanin's Historic Strolls
- Description of guide-led historic walking tours, schedules and ticket information.
- http://www.historicstrolls.com/

Spirit Cruises
- Cruises and tours on the Potomac River featuring lunch and dinner, live entertainment, and sightseeing.
- http://www.spiritcitycruises.com/dc/bridge.jsp

Gilt-Edge Luxury Tours & Travel
- Private tours of Washington, DC and surrounding areas with personal guide in luxury sedans,limousines, vans or mini-busses. Categorized tours, newsletter and rates.
- http://www.giltours.com/

Capitol River Cruises
- Potomac River cruises and charters.
- http://www.capitolrivercruises.com/

Tourmobile Sightseeing
- Operates daily narrated tours of major tourist sites. Information on tours offered, the stops along the way and buying tickets.
- http://www.tourmobile.com/

Bike the Sites
- Offers guided interactive bicycle tours, morning exercise rides and bike rentals. Includes online booking.
- http://www.bikethesites.com/

Zohery Tours International Inc.
- Offers multilingual tours and transportation. Includes rates, online reservations and a newsletter.
- http://zohery.com/

Historic Tours of America: Washington, DC
- Operates Old Town Trolley city tours and amphibious DC Duck land and water tours. Tour descriptions and online ticketing.
- http://www.historictours.com/washington/

Heritage Tours
- Offers personalized tours, "meet and greet" services, and entertainment planning for meetings or conventions.
- http://www.heritagetoursltd.com/

Washington Walks
- Guided walking tours. Information on the itineraries, schedules, and rates.
- http://www.washingtonwalks.com/

Guild of Professional Tour Guides of Washington, DC
- Membership organization of licensed professional tour guides and tour operators. Includes information about the guild and about being a tour guide.
- http://www.washingtondctourguides.com

Tour-One: White House Tours
- Narrated tours of the White House and DC monuments. Offers daytime, nighttime, and customized tour packages.
- http://www.whitehousetours.com/

Points of Interest
- Guided tours of Washington DC, Baltimore, Annapolis, and Historic Southern Maryland.
- http://points-of-interest.com/

Georgetown House Tour
- A tour of Georgetown's homes and gardens held on a weekend at the end of April. Different houses shown on Saturday and Sunday. Ticket includes afternoon tea.
- http://www.georgetownhousetour.com/

UC Tours
- Specializes in multi-cultural historic touring. Includes programs.
- http://uctours.com/