Nope, in all the years I've played on here the only "cheat" is someone giving away games by leaving in the middle of the game.  This of course only applies to billiards as I don't play the other games, but I believe Larkinor had cheats but I'd assume they took care of them by now (quite some time ago it was).

If by 'line cheat' you mean a 

path

 (From the billiards practice mode) that can be used on the online version too, then no, there is no such cheat. More accurately though the cheat, if it exists, is not available to the majority....although I'm sure we would know about such a cheat if someone used it :). 

The line cheat is 100% not real ;) 

If it was im sure we'd know by now, im sure the best hackers in the world could get something out of the Pc game but im probably wrong :p.

The only program we had against Fod was one around 3-4 years ago, i dont know 100% how it worked as i only seen the program but didnt use it as i wasnt sure how to, but im sure Matt could fill you in on how to :p.

It was something like when you was on the last colour or red in snooker, you typed in the score of the match if you were[ b]losing

 it, then pot the last ball and if you lost, you wouldn't lose any of your rating, but if you won you carried on as normal gaining.

Im not sure how they created it or how they got it on here but i remember seeing a certain player ive already mentioned using it for about 2 month until he got caught ;).

Path cheat never existed.  Ive heard rumours that there are people using this program, but i dont believe it exists.

What is the point of cheating anyway? To get crown?  Wow, nothing really worth cheating about is it?