I've been thinking about the whole "I need tabs in Safari" issue, and have come to realize that no, in fact, I don't need tabs in Safari.
What I need is a way to manage multiple open web pages in a single window. Tabs are only one implementation of this. And they tend not to scale well (open 15 pages as tabs in Chimera to see what I mean).
What would work is some way to list any number of pages associated with a single window. Something like the Bookmarks mode in Safari is a good start. It makes it easy to list pages, but it's modal.
How about a hybrid approach, one that uses the bookmarks interface from the Bookmarks mode, in combination with the Browse mode?
I've done a quick and dirty mockup of something that approaches what I'm thinking about. Take a look at this, and let me know what you think.