Ryan Shawcross for stoke fc has an amazing throw (doesnt need the flip)
he can throw it form the touchline to the middle of the penalty area.
teams have caught on and put advertising boards close to the pitch to stop his run up, lol
ya it's allowed. you just can't go over the line, the ball has to come from behind/over your head, you have to throw the ball from where it went out - or within a yard of it, and you have to face the field - so you can't throw it backwards.