ℹ information source, U+2139
⏩ black right-pointing double triangle, U+23E9
⏪ black left-pointing double triangle, U+23EA
⏫ black up-pointing double triangle, U+23EB
⏬ black down-pointing double triangle, U+23EC
▪ black small square, U+25AA
▫ white small square, U+25AB
◽ white medium small square, U+25FD
◾ black medium small square, U+25FE
◻ white medium square, U+25FB
◼ black medium square, U+25FC
⬜ Large white square, U+2B1C
⬛ Large black square, U+2B1B
☑ ballot box with check, U+2611
⚪ white circle, U+26AA
⚫ black circle, U+26AB
🔴 red circle, U+1F534
🔵 blue circle, U+1F535
🔘 radio button, U+1F518
🔲 black square button, U+1F532
🔳 white square button, U+1F533
🏕 camping, U+1F3D5
⛺ tent, U+26FA
⛽ fuel pump, U+26FD
✅ white heavy check mark, U+2705
✔ heavy check mark, U+2714
✳ eight spoked asterisk, U+2733
❎ negative squared cross mark, U+274E
➡ rightward black arrow, U+27A1
⬅ leftward black arrow, U+2B05
⬆ upward black arrow, U+2B06
⬇ downward black arrow, U+2B07
🔍 magnifying glass tilted left, U+1F50D
🔎 magnifying glass tilted right, U+1F50E
📖 open book, U+1F4D6
⚙ gear, U+2699
Don't get too attached to what these look like. They render quite differently from platform to platform, and they render differently in Chrome versus in Safari on a Mac.
These extended characters render in Safari on iOS 9, but they don't scale with alphanumberic characters when size is adjusted in em as they should. Maybe they scale a litte, but not as much as they should, not as much as alphanumeric characters do.