from http://www.unicode.org/charts/PDF/U27C00.pdf

Unicode characters x'27C0' through x'27EF'

Wish I knew a font that had these characters in it.ED

Miscellaneous symbols
⟀ 27CO THREE DIMENSIONAL ANGLE
• used by Euclid
⟁ 27C1 WHITE TRIANGLE CONTAINING SMALL WHITE TRIANGLE
• used ty Euclid

⟂ 27C2 PERPENDICULAR
    >> orthoganal to
• relaion, typeset with additional spacing
- 22A5 up tack

⟃ 27C3 OPEN SUBSET
⟄ 27C4 OPEN SUPERSET
⟅ 27C5 LEFT S-SHAPED BAG DELIMITER
⟆ 27C6 RIGHT S-SHAPBD BAG DELIMITER
⟇ 27C7 OR WITH DOT INSIDE
⟈ 27C8 REVERSE SOLIDUS PRECEDING SUBSET
⟉ 27C9 SUPERSET PRECEDING SOLIDUS

Vertical line operator
⟊ 27CA VERTICAL BAR WITH HORIZONTAL STROKE
- parallel with honzontal stroke;
~2AF5 triple vcrti
Miscellaneous symbol
⟐ 27DO WHITE DIAMOND WITH CENTRED DOT
Operators
⟑ 27D1 AND WITH DOT
    >>2227 logical and
    >>2A40 intersection with dot
⟒ 27D2 ELEMENT OF OPENING UPWARDS
    >> 2AD9 element of opening downwards
⟓ 27D3 LOWER RIGHT CORNER WITH DOT
  ==pullback
-230B right floor
⟔ 27D4 UPPER LEFT CORNER WITH DOT
  ==pushout
-2308 left ceiling
Database theory operators
⟕ 27D5 LEFT OUTER JOIN
⟖ 27D6 RIGHT OUTER JOIN
⟗ 27D7 FULL OUTER JOIN
    >>2A1D join
Tacks and turnstiles
⟘ 27D8 LARGE UP TACK
- 22A5 up tack
⟙ 27D9 LARGE DOWN TACK
- 22A4 down tack
⟚ 27DA LEFT AND RIGHT DOUBLE TURNSTILE
-22A8 >true
    >>2AE4 vertical bar double left turnstile
⟛ 27DB LEFT AND RIGHT TACK
-> 22A2 right tack
⟜ 27DC     >> LEFT MULTIMAP
    >>22B8— multimap
⟝ 27DD     >> LONG RIGHT TACK
-> 22A2 right tack
⟞ 27DE     >> LONG LEFT TACK
-> 22A3 left tack
⟟ 27DF UP TACK WITH CIRCLE ABOVE
    >> radial component
    >> 2AF1 down tack with circle below
Modal logic operators
⟠ 27EO LOZENCT DIVIDED BY HORIZONTAL RULE
• used as form of possibility in modal logic
    >>25CA lozenge
⟡ 27E1 WHITE CONCAVE-SIDED DIAMOND
  == never (modal operator)
⟢ 27E2 WHITE CONCAVE-SIDED DIAMOND WITH LEFTWARD TICK
  == was never (modal operator)
⟣ 27E3 WHITE CONCAVED DIAMOND WITH RIGHTWARDS TICK
  == will never be (modal operator)
⟤ 27E4 WHITE SQUARE WITH LEFTWARD TICK
  == was always (modal operator)
    >>25A1 white squarc
⟥ 27E5 WHITE SQUARE WITH RIGHTWARDS TICK
  == will always be (modal operator)

Mathematical brackets
⟦ 27E6 MATHEMATICAL LEFT WHITE SQUARE BRACKET
  == z notation left bag bracket
    >>301A left white aquaro bracket
⟧ 27E7 MATHEMATICAL RIGHT WHITE SQUARE BRACKET
  == z notation right bag bracket
    >> right white square bracket
⟨ 27E8 ( MATHEMATICAL LEFT ANCLE BRACKET
  ==bra
  == z notation left sequence bracket
    >>2329 < left-pointing angle bracket
-3008 < leftanglebracket
⟩ 27E9 ) MATHEMATICAL RIGHT ANGLE BRACKET
  ==ket
  == z notation right sequence bracket
    >>212A right-pointing angle bracket
    >>3009 right anglebracket
⟪ 27EA MATHEMATICAL LEFT DOUBLE ANGLE BRACKET
  == z notation left dicvJon bracket
-300A left double angle bracket
⟫ 27EB MATHEMATICAL RIGHT DOUBLE ANGLE BRACKET
  == z notation right dicvJon bracket
    >> 300B right double angle bracket
Wonderful, now that there are all these cute symbols,
How do you get them to display?
Download the DejaVu fonts(Public Domain) and unzip them to your fonts directory .

Almost any HTML tag can include :