Asterism ⁂
(Unicode character U+2042 and HTML symbol ⁂ as well as Alt + 8258 on Windows)
Used to 'indicate minor breaks in text,' call attention to a passage, or to separate sub-chapters in a book.
Currency Symbol ¤
(Unicode character U+00A4 and HTML symbol ¤ or ¤ as well as Alt + 0164 on Windows)
Used to denote a currency when the symbol for the particular currency is unavailable.
Interrobang ‽
(Unicode character U+203D and HTML symbol ‽ as well as Alt + 8253 on Windows)
Used in various written languages and intended to combine the functions of the question mark … and the exclamation mark.
Sound Recording Copyright Symbol ℗
(Unicode character U+2117 and HTML symbol ℗)
The copyright symbol used to provide notice of copyright in a sound recording (phonogram) embodied in a phonorecord (LPs, audiotapes, cassettes, compact discs, etc.)
Commercial Minus Sign ⁒
(Unicode character U+2052 and HTML symbol ⁒)
The commercial minus sign was and is widely used in bookkeeping to indicate a minus sign. On typewriters a ./. was written instead.
to be continued … ;)