Hello Thomas,
As far as I know there is no option/tool to do that inside iWeb.
(Ex : find & replace works only in 1 page)
There are some third-party applications that work alongside iWeb.
Ex with iWebBuddy you can enter code to be added to the header and/or the footer per Site.
For your situation, check out [TextWrangler|http://www.barebones.com/products/TextWrangler>.
It's great freeware. One of it's features is "mass" find&replace = you can apply find&replace to all files in a given folder/subfolders.
You do this on the published HTML files on your iDisk (or in the local folder if you publish to a Folder).
Adding code to the bottom is easy : you do a find for the HTML tag </body> and replace it with your_code </body> (so your code will be added above the </body> tag).
Adding code at a specific place in the body can also be easy IF at that place there is a unique string of code in all the pages that you can use for the Search.
If that is not the case, then in iWeb you'll have to enter (by hand) some unique find-code yourself.
Ex, at the location where you want the coffee add : create a textbox and type something like AAAAA.
(something that is unique in all pages), after publishing, you'll enter this AAAAA in the search field of TekstWrangler.
Now, the problem with editing the HTML files is that iWeb overwrites them when they are republished. (a page that was changed in iWeb)
So you'll have to do the whole process all over again.
Here comes the real power of TextWrangler : it fully supports Apple's AppleScript.
When you open TextWrangler, start with "record script", do your thing and when ready, save script.
Next time you need to add the coffe code to new or replublished pages : Run the script and have a coffee yourself 🙂
On my Blog about adding [Favicons|http://www.site49.eu/Leo/Tips4Mac/Entries/2009/2/15_Favicons.html|Add favicons to iWeb websites] you can find some screen shots on how this mass find&replace works in TextWrangler.
Kind regards,
Leo