Most of the PTC sites require you to put in either your Paypal ID or Alertpay ID. These are just like your online bank accounts where your earnings are deposited. I've listed down the most commonly used e-currency sites:

1. Paypal - affiliated with eBay, so if you want to open your own eBay store, you might want to consider opening paypal account. All you will be needing to get your account verified is a credit card. But for those who doesn't have credit cards, you might also want to open an EON account with Unionbank. It's a savings/debit card.
2. Alertpay - you will be needing a photo ID and proof of address to be verified. It's same as paypal except that some sites only accept alertpay
3. Moneybooker - you can use this with eBay stores as well. In order for your account to be verified, you have to request for verification letter to be sent to your home address which contains a 6 digit verification code that you must enter to verify address.
4. Liberty Reserve - they offer you a list of merchants where you can use your liberty reserve account most of which are for FOREX

These are the sites that I've signed up for but uses paypal more often than I use the others. If you want to sign up, I recommend that you read their terms and conditions as well as their privacy policy first. There are other sites though that I haven't tried yet. You may also want to check them out.

e-Currency Sites