Keyboard shortcuts for symbols on Mac OS X

Degree (˚): option + k
Micro (µ): option + m
Copyright (©): option + g
Ohm (Ω): option + z
Registered (®): option + r
Trade mark (™): option + 2

Math:
Approximate (≈): option + x
PI (π): option + p
Delta (∆): option + j

Infinity (∞): option + 5
Division (÷): option + /
Not equal (≠) : option + '+'

Plus/Minus (±): option + shift + =

Square root (√): option + v

Alpha (∂): option + d

Beta (ß): option + s

Function(ƒ): option + f

Calculus (∫): option + b

Money:
Yen (¥): option + y
Pound: (£): option + 3
Euro (€): option + shift + 2