I am new to this website and am hoping someone can offer me some good advice.
I have an 8 month old GSD. We have had him since he was 8 weeks old. He has always jumped up and we have always discouraged this as we have a 2 year old toddler in the house - although I have to say he never jumps at my little boy he saves this behaviour for any adult who happens to come along!!! I have taken him to dog training lessons and most other disciplines he has picked up really well.
I have tried positive reinforcement with treats and toys, rewarding him when he doesnt jump. He only gets fuss and attention when he sits not when he jumps. I have tried the method of folding my arms and turning my back on him and am now sporting several large black bruises where he continued to throw himself at me. When I ignore his jumping he has now started to jump and bite at my arms. If I go into another room and only return when he has calmed down he instantly gets excited and starts jumping again. I'm at my wits end with it. It has got to the point where I lock him away when visitors come because most people do not want 6 stone of dog jumping all over them.
I don't advocate harsh treatment but have even tried a rattle bottle after seeing it used on Dog Borstal. That worked with us but he is too excited when strangers come and totally ignores it. And if he sees I'm not in possession of the bottle then the jumping starts again. To me this is ruling with fear and not control so I don't really want to continue with that method.
If anyone else has had similar problems and managed to resolve it I would love to hear from you.

We managed to stop the jumping up before it developed into a habbit (2 days as a pup - wow we were lucky :) ), but what we had problems with was mouthing & pay-biting visitors due ot excitment :(

Rather than try to stop the mouthing/play biting, I got his attention before he had chance to start and got him laying down (he'd calm down quicker that way). I'd use treats to get his attention and treats to rewards quite often for staying laid down, at first I had to keep him on a lead, but gradually as he got the message (visors = go to kitchen & I'll get treats if I sit/lay and not chew on the  visitors) I stopped needing the lead.

It did take a while, but was defiantely worth the time invested. My parents will come into my house without knocking, when Buster was younger I had to keep my door locked or he'd be hanging off thier sleves and being a complete idiot, but now I leave my door unlocked, as soon as he hears somebody coming in, he'll run towards the door to greet them, but I only have to say 'kitchen' and he'll tank on back to there to wait for his biccy even before he's greeted the visitor :-D

The only thing I find now that treats are being phased out, is that Buster will go up to a visitor & poke them in the leg with his nose, he'll then look at me as if to say "see, I was gentle, were's my biccy?'. (obviously rewarding gentle interactions had sunk in at the same time as stopping the general loony behaviour)

Thank you Mastifflover. I will certainly try this method at the weekend when my parents come down (I don't mind using them as guinea pigs!! lol). He is a mouther too so it could be a double whammy!!!

I have dogue de bordeaux which I can't let jump up at people due to their sheer weight !
My bitch pup who is ten months now would jump up at me everytime I walked into a room she was in , if I was cooking at the hob she would jump up at my back ( just to let me know she was there )
Well I couldn't have this so nipped it in the bud very quickly just by voice commands , when she jumped I said NO in a raised voice . I know it's simple and you've probably tried it but saying the command at the right time and in the right tone really worked for my youngest . I did reward her with treats at the beginning aswell but just cut them out when I knew she'd actually " got it!"
I personally wouldn't recommend the bottle as I've heard you can do more damage if not done at the right time ( not the method I'd like to use )
I hope you get some more advice and soon see some results.

You need a clicker, and bag of very tasty treats.  You also need an able bodied assistant to hold your dog sat on lead, to  heel.  You approach them from about 20 yards away, calling their name, encouraging them to jump up.  The second they move, you turn away and go back to the start.  The only thing the assistant needs to do, is not to get pulled over, and to pop him back to heel, in a sit.  Keep repeating until he tries staying in a sit, at which point click and reward, the timing has to be spot on, and he can't have moved his bum one inch.  They do know there is a way to get the reward, and try everything, including barking, so it takes a bit of patience.  You also need to train with different people and in different situations, inside, outside etc, so that he learns to associate the training to mean he has to sit calmly for everyone, in any place.  As he gets better at sitting and waiting, you can increase the time between click and treat. 

If none of the above remedies work you could always try teaching him to come up on command. :-) I d that with my boy as I found it far easier to do than any of the above. He ignored all other attempts to stop him jumping up.