I've been frustrated with Safari's lack of a "Save tabs" as bookmark folder method. Combining a couple of posts mainly this one, I wanted to share a solution. First, download, compile and save this safari_tabs script in your Safari "Scripts folder." From there, when you activate it, it will iterate through every tab of every window and create a bookmark folder with a bookmark for each tab. Note, this is not localized, and has been tested with 10.3.5
[robg adds: I have not tested this one...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040917211924222