well, there are a couple of symbols for technical and other stuff, eg: ⌘⌨⎙ↀ☕⚠♼◷◳ ▄ ◙ ▶ ▸ ▣
Flowers: ❀ ✿ ❁ ✾
...the symbols of Yi-King 𝌎
...Braille-Dots ⡽⠑
and loads of arrows: ☟➲⬇⤵

And don't forget all the foreign languages ぺぴ〱ッㄛت ك
and simple pictograms from pictographic languages like Kanji 二人冂凵凶口巛山彡日曰田疒訁

Well, you get the idea...
...though some of them are quite tiny and not really useable. For Movies, I use "TV", btw :-)


There are also lots of custom fonts with icons out there (like Dingbats), but I'm quite sure they won't work as Bookmark Labels; but you can also use any special character that can be rendered with HTML and Unicode.

My favorites are arrows (→) for "send to"—such as Posterous—and ligatures. I also use ligatures to weasel in under the 140-character limit in Twitter. fl, ff, ffi, ffl, etc. are all nice little cheats when you're a character over and don't want to rephrase.