In terms of writing obscure letters with keyboards, I believe it is cheating to use Alt-codes. I do not use them, and I can create all of these with my keyboard (not including the normal keys):

by just pressing up to 3 keys together at the same time:
`Ќ!"Ѓ$%^&*ЙВГ€НОЁ⅛ЃМ⅜⅝⅞™БАПłЖŧ←↓→јўцп№đŋħjĸłЋЛЂ“”n ЕЗΩŁЎŦЅ↑ıиоЦЇаЊŊĦJ&ŁЉ‘’NКзї

by pressing up to 3 keys together, followed by another key (dead keys):
фыяіќџФЫЯжмŸхůХŮуĩёѕũУĨбеŨāēīōūĀĒĪŌŪсćщэĺńѓŕśњ§źСĆ ЩЭĹŃгŔŚкнŹűŰтъюєћТЪЮдлčďěľňřšťžČĎĚĽŇŘŠŤŽршьђљРШЬвй ăğĂĞ

My keyboard is not special either:
http://toribash.reversers.org/qwerty...c-keyboard.jpg