I really enjoy having folders on my Bookmark-Toolbar in Firefox. They allow me to group sites with similar themes, or sites I usually check at the same time.
But The toolbar can quickly fill up with wordy descriptions, and there's nothing worse than a filled Firefox toolbar. That's why I've started using symbols as indicators for what lies beneath. In the picture you can see my symbols for sites that change often (delta), security sites (squiggly S) and torrents ( the cross being fed with arrows). This way I associate the cool symbols with the actual things they represent (and I think it looks cool too).
To get these symbols, the alt / option key is your friend. Recently a friend of mine was happy to find out that the é symbol could be easily created using the alt+e, e combinition.
If you have trouble remembering whats underneath your standard keys Quicksilver can help. Simply start it up and start typing "Keyboard". It should come up with the "show keyboard viewer" application. This shows you what you are typing now and what are the possibilities from the various function keys.
This is a great little feature that I believe is built into the OS but Quicksilver makes it trivial to access. I plan on using this function to demonstrate different keyboard short-cuts to people in the future.