U+F8FF is (in a way) part of the Unicode standard as the last of the private use characters - so it's appearance is not standardised by Unicode.
Some early Tengwar fonts map Elvish characters to it. The Imitari font
draws it as a capital eth.
The font Luxi draws it as the euro symbol.
The font "Standard Symbols L" uses it as one of the box drawing
The official PRC standard on precomposed Tibetan uses the
codepoint for the Tibetan syllable "hwo".
Some font makers place a
copyright statement or other creator's mark at that code point. For
example, the dingbats font "DavysDingbats" uses it to display a face,
presumably that of the font's creator.
In most Apple-supplied fonts,
it represents the Apple logo, or an early version of the command key.
On Macintosh computers with the US keyboard layout active, the
keyboard shortcut for the symbol is Option-Shift-K.
Unicode Registry suggests it be used for the Klingon glyph "KLINGON
MUMMIFICATION GLYPH." This is followed by e.g. Code2000.
1, is the Windows logo. In some computers, however, it is (U+F000)
instead of .
Note: On XP, Wingdings has the MS Windows logo at 0xFF.