As mentioned before, thanks to del.icio.us bookmarking site and excellent Firefox plugin with the same name, I have almost perfect solution where to keep and how to organize my bookmarks. In theory, I will never loose anything interesting. Or will I ?
The good news and the bad news about bookmarks is that they are very dynamic. What you've stored in your favorites or del.icio.us may disappear without warning and never come back (actually, thank's to Google caching it is not so bad, but even Google cache will eventually expire). In situation like this, I always wish to have captured not only link but the whole copy of the page(s).
This is exactly situation where Scrapbook is the perfect tool. With Scrapbook extension, you can very easily capture content of current page or current selection on the page and add it to your collection of saved fragments - your digital scrapbook. The content is saved nicely, with most features such as images, CSS or dynamic content preserved (local links are overwritten and so on). You can even organize your clippings into folders, manage them (delete or combine content), import or export them to very good looking HTML.
It is very easy to maintain several scrapbooks (for example by area of content or by project), everyone with folders. Later on, you can combine them, move content between scrapbooks, merge two scrapbooks or split one into two.
In newest version, it is very easy capture subtree - page with sub-pages - with limiting the depth of links and selecting type of linked files to download. For example JPG or MP3 - or whatever you want - but do not get me wrong, I do *not* recommend or even suggest that you should download MP3's - this is what iTunes was invented for ;-).
Some of the other bookmarking sites save snapshot of the Web page when you bookmark it, which can sound better than having your bookmarks in one place and your saved pages elsewhere. I still like scrapbook better, though, because I can work with saved content offline and working with content takes lots of time. Most of the content I save (unlike URL's) needs some processing and have it available offline is very handy when you have your Macbook and some time available but no internet (for example at skating rink) ...
Here is one little trick I use to overcome problem with multiple scrapbooks on multiple computers and their consolidation: on each computer I use, I create special scrapbook with same name as computer name (use Tools->Extensions, Scrapbook -> Preferences->Advanced and enable multiple scrapbooks first). This will be your default scrapbook for that machine. When you later on synchronize all computers against shared network disk (using any tool you want, e.g. Offline Folders or rsync), no information will be overwritten and you will have available all information from any Firefox - as long as the network disk is visible - to consolidate the content. And btw, the content is platform agnostic - scrapbooks created on Mac can be processed with Firefox on Windows and vice versa.