Have you ever wondered if your viewer and computer were rendering Second Life™ correctly? Do you see what other users see? And if you compiled a viewer, is it rendering things correctly? The answers to those questions can be found at Bug Island.
Of course showing up there and looking to see what you viewer shows you is only half the answer. You also need to know what things are supposed to look like. The SL Wiki shows you the pictures and behaviors, in movies, of what you should see. SL Wiki page: Bug Island Test.
Dan Linden makes frequent updates to the wiki page. This suggests it is a useful and active part of the Linden development effort.
If you are helping test viewers, this is a handy resource to know about. Also, if you think your viewer is not working right after a video driver update, this is a place to check things. It is also handy for helping explain what and why you think something should be rendered a certain way. If things do not match the Bug Island reference images and behaviors, by definition something is not right, which should catch a Linden’s attention. Giving them a picture taken with your viewer for comparison is convincing.
Oh… and if you didn’t notice. On the Chrome browser the CSS style sheet controlling the wiki is messed up… or Chrome is. The links and search tool on the left side slide down below the content. I see the problem on my phone and desktop.
IE8 and 11 handle the wiki pages OK as does Firefox and Safari.