A Blender artist called Antonio Gessi, has published a very cool guide about the Fluid Simulator options. To make this guide even more interesting, all parameters are illustrated with animations. For instance, when he explains how the Domain option works, there is an animation showing how the fluid will behave at different resolutions.
Like the author says, this is not meant to be a tutorial. It`s just a guide, explaining how most of the parameters work. If you still don`t knows how to setup the Blender Fluid simulator, or want to know more about it, you can`t miss that! Visit this link to check out the guide.
Update (24/11/07): Antonio has moved his site; the link is working again.