Use right Alt button + number pad (not the numbers above the key board)
Alt + 156 = £
Alt + 36 = $
Alt + 155 = ¢
Alt + 0128= €
Alt + 167 = º (degrees)
Alt + 24 = ↑
Alt + 25 = ↓
Alt + 26 = →
Alt + 27 = ←
Alt + 29 = ↔
Alt + 18 = ↕
Fun symbols:
Alt + 3 = ♥
Alt + 11 = ♂
Alt + 12 = ♀
Alt + 13 = ♪
Add more if you know of others