I was under the impression that all macs came with iLife?
I suppose it isn't "free per se" but you did already pay for it, so you might as well use it...
Does anybody treat iWeb as a serious application?
If you are really good with HTML, what you need is a simple TextEdit (as part of your OS X, or any basic text editor). If you want to use CSS, Espresso might worth trying.
If you are good with graphics, code and don't want to create a website by using code primarily, try Photoshop and DreamWeaver.
If you are either, you might want to give RapidWeaver a try, but expect to spend extra on plug-ins to open its true potentials. Realistically, you need a couple on top of Stacks, which I think is a must ($25). Personally, I spent about $150 on RW themes and plug-ins so far on top of owning RapidWeaver. RapidWeaver is the most flexible option in a way that you can progress from being a beginner to a fairly proficient user. In a way, it is probably the best way to take you to the height of Photoshop/DreamWeaver by Adobe.
You may use Pixelmator for graphic tasks or open-source editors like Gimp or Inkspace. I think Acorn now has a limited free version, if you want a very basic picture editor. All websites use some form of graphic elements, so you might get familiar with graphic design too.
Of course, you may use iWeb. But has anybody seen a website that was created with iWeb? I'm not talking about your own or friends of yours'. Using iWeb is considered a very inefficient and unprofessional way to create websites. Just as well, you may use a template with a text editor. There are some nice HTML and Flash templates. The latter actually allows you to create professional-looking sites very easily.
Also, I never, never, never saw an iWeb page (including mine some years ago) that loaded quickly. People moan about Flash but Apple's idea of web design for the masses is not better either. So, if you want to use iWeb, your main option to reduce loading time and size would be by keeping your graphic stock under control. Some people also go mad about the folder structure of iWeb. Admittedly, It's super easy to use and for little effort, you actually get a functional website that looks nice, unless you really mess it up.
NVU is open source, there used to be another cheap or free one called 'GoodPage'. There are some cheap WYSIWYG (what you see is what you get, like iWeb) editors but you have to remember that it's never like that. Often what you see is something like what you may get.
Check out these ones:
http://webdesign.about.com/od/macintoshhtmleditors/tp/free-macintosh-editors.htm
EDIT:
sorry for the difficulty reading the above, but I'm multitasking.
Good luck with your site(s)!