I've found del.ici.ous to be a fantastic bookmark organizing tool. I don't know all the ins and outs of it yet, but I can say that I like the following features:
1) having access to all my bookmarks from any computer;
2) being able to 'tag' my bookmarks to group them into categories;
3) being able to search within my bookmarks;
4) being able to add a comment to each bookmark. I mostly use this feature to leave myself a note as to why I bookmarked the site in the first place if it's not obvious.
There are two macros to download for your web browser. The most important of these reads 'post to del.icio.us'. While having a page open, you just hit this button and it takes you to the del.icio.us page where you can add tags and info. Then, you're taken right back to your page. The other macro is 'my del.icio.us' which is a shortcut to your bookmarks.
There are other, social, uses for del.icious.us, but I haven't explored them yet.
"Life's but a walking shadow, a poor player that struts and frets his hour upon the stage and then is heard no more. It is a tale told by an idiot, full of sound and fury, signifying nothing."