Kongs are GREAT! You can get different "grades" for different chewers too... So if you have a destroyer get I think it's a black one...

We have a german shepherd who LOVES his tennis balls/balls, and was going through about 5 a week.

Mum also just bought him a spikey ball that seems pretty solid that he also loves - he tried to nibble the spikes off (no such luck though), I'll have to find out what brand it is and get back to you...

That's a small dog thing - I think they have a complex because they're so little, so they need to prove that they're just as good as the big dogs! My parents have a jack russell & a german shepherd, and watching those two play is hilarious. The German Shepherd will actually go into a drop and let the Jack Russell jump all over him and bite at his ears & mouth and everything. The thing is, the Jack Russell is over 10 years old, and the German Shepherd isn't even 2 yet!
haha. My parents neighbours had a jack russell, mum and dad had a GSD, and they both used to do the same thing. Just goes to show German Shepherds are sooks!