How safe are they to use on the internet? You don't use a pin number and you don't sign for authorisation but you do give out all the details on your credit card. I don't usually think about it but while buying something today, it just came to mind.
If the payment page has a closed padlock or an unbroken key on the screen (usually in the bottom right hand corner), this means that your payment details will be secure :o)
As long as you have your cards protected by your bank or a company like CPP then even if your cards are used fraudulently they will cover the cost anyway, although its ideal if this doesn't happen in the first place. A good firewall and anti spyware on your computer helps too as this blocks anyone from hacking in to your computer.