Bernd Schneider's excellent and extensive Star Trek site, which has everything from ship lists and images to articles and episode reviews. You really can't find a much better Star Trek website on the web.
Masao Okazaki's work, consisting of what he imagines as historical Starfleet and Earth starships. Included are many images and extensive historical write-ups.
Anti Drone's ambitious projects - one to create the most detailed blueprints I have ever seen, anywhere, of any ship, and the other to create a comprehensive episode companion to the series Star Trek: Enterprise.
Ivymae's impressive, hand-drawn Enterprise artwork.
Contains an extensive amount of information, multimedia, and screencaps from every episode and movie in the Star Trek franchise.
Otten's excellent behind the scenes look at the Star Trek franchise. What began as a look at Star Trek: Phase II has expanded to include TOS, the feature films, TNG, and DS9, utilizing both concept art and interviews from the artists who made it.
A group of artists dedicated to the design of starships that were mentioned, but never seen on screen. It has been inactive for the most part lately, but it still has a lot of interesting designs to look at.
Another good fan-based ship design website, open to submissions from anyone.
A website dedicated to fixing all of the instances of discontinuity throughout the run of the Star Trek franchise. Anyone can contribute articles, just be sure to read the process for doing so before you start.
Just like the name says, this is Kevin Thomas Riley's Enterprise site, which contains reviews and images from the show and from many of actress Jolene Blalock's numerous photoshoots.
A massive Star Trek wiki that focuses on canon incarnations of Star Trek. It is one of the most comprehensive resources you will ever find about Star Trek, with even more information than the encyclopedias, and constantly brought up to date.
A website/messageboard that features work from both 3D and 2D artists who make some of the best sci-fi art you will ever see, for a job, or just for fun. The only catch is that you have to register on their forums to view any of the attachments.
Doug Drexler’s personal blog, where he shares pictures and stories from his work on Star Trek and other sci-fi series. Definitely worth a visit.
The website now famous for the "Save Enterprise" campaign. Affiliated with many other websites, it supports a large community and has a large public messageboard.