Very easy to realize via CSS, use the Unicode value for the symbol.
(Doesn’t work in IE, of course.)

a.internal:hover:after { content: " \21AA"; /* unicode value */}

Some unicode arrows:

21A8↨up/down arrow with base
21A9↩leftwards arrow with hook
21AA↪rightwards arrow with hook
21F0⇰rightwards white arrow from wall
21E1⇡upwards dashed arrow
21E2⇢rightwards dashed arrow
21E3⇣downwards dashed arrow
21E4⇤leftwards arrow to bar
21E5⇥rightwards arrow to bar
2192→rightwards arrow
2193↓downwards arrow
2194↔left right arrow
2195↕up/down arrow
2196↖north west arrow
2198↘south east arrow
2794➔heavy wide-headed rightwards arrow
2798➘heavy south east arrow
2799➙heavy rightwards arrow
279A➚heavy north east arrow
279B➛drafting point rightwards arrow
279D➝triangle-headed rightwards arrow
279E➞heavy triangle-headed rightwards arrow