4cruises
A cruise booking site that also handles air, hotel and car reservations.

American Safari Cruises
Small yacht trips through the California wine country, Alaska's Inside Passage and Mexico's Sea of Cortez.

CDC Vessel Sanitation Program
Rankings of ships on cleanliness and sanitation by the Centers for Disease Control.

Cruise411
An extensive directory of cruises where you can book your next voyage.

Cruise Critic
Frank opinions and reviews of dining, cabins, recreation and entertainment.

CruiseMates.com
With cruise reviews (from experts and readers), ship itineraries, last-minute bargains and tips for first-timers, this is an excellent resource for selecting a voyage.

CruiseOpinion.com
Thousands of personal reviews, sorted by cruise line and ship, but this site has not been updated for at least two years -- don't let the current date fool you.

CruisePage.com
Assessments of hundreds of cruises and a discussion forum.

Expedition Cruises
Leading discounter - sometimes has rooms at hotels listed elsewhere as sold out

iCruise.com
Leading discounter - sometimes has rooms at hotels listed elsewhere as sold out

Small Ship Cruises
An excellent directory of alternatives to megaships, this site lets you search by destination, theme, or cruise line -- you can book here as well.