Cavy-Care.Com : An online guinea pig care guide

Before I start listing safe guinea pig toys, I want to mention a few toys on the market which are actually very dangerous for piggies:-

Exercise balls & wheels:-
Run-around exercise balls and wheels are very dangerous for cavies. Even the guinea-pig sized ones. Guinea pigs are not 'built' to run around in a ball/wheel - their bodies are not as flexible making them unable to cope with the requirements of a ball/wheel.
If you use one of these with your pigs, please stop. They have been known to break pigs' backs and damage their precious paws.
No ball or wheel is suitable, whatever size, since all wheels and balls require arching of the back.
Guinea pigs aren't hamsters, mice, chinchillas or any other ball-and-wheel animal. Don't treat them like one.
Harnesses & leashes:-
There are many of these guinea pig harnesses and leashes on the market. Unfortunately they are just as dangerous as exercise balls. Even a slight tug on the harness could cause pig's ribs to fracture. If a pig gets spooked, your guinea may sustain horrific injuries such as fractured ribs and even spine - boht of which are very painful and difficult to treat.
Piggies are not like dogs, who need walking under control (on a leash) every day. Cavies need time to run free in their own space, at their own rate, and do not like being restricted in such a way.

Why are these toys sold if they are dangerous? Because they keep selling. The more people buy guinea pigs balls and wheels, and harnesses and leashes, more will continue to be made. The majority of manufacturers won't stop making a popular, well-sold product unless a very clear health warning is issued to them by many people or an influential body.
Warn everyone you knwo who has a guinea poig against these products and ask them to spread the word - these products will onyl be off the market when we stop buying them.

Chew Toys are also very unnecessary. Even if a guinea pig were interested in chewing one up, it only does half a job. Guinea pigs have 20 teeth - four incisors, the ones you can see at the front of the mouth, plus 16 molars - four on each side, top and bottom, at the back of the mouth. Gnawing on any chew toy only succeeds at slowly wearing down the incisors, leaving the molars with no aid at all. Chewing on stained, flaky wood can sometimes cause splinters, which are very undesirable especially when it could have been avoided.

The toys listed are hereon are cavy-friendly and enjoyed by many guineas worldwide.