1. Payoneer

Payoneer is very similar to the other international services on this list. Probably what makes it truly different is that with it you can get a virtual U.S. bank account. This is of great importance to everybody who is not in the US but who needs to get money in a U.S. bank. (If this might pose legal issues in your country, check with a local lawyer.)
As for fees, Payoneer is not cheap. First, it has an annual fee of $29.95. Second, withdrawal from an ATM costs about $3. Third, there are transaction fees (they differ based on volume and location).
Despite its high fees, Payoneer has managed to become popular. Many sites now accept it, and some of the best affiliate marketing networks have embraced it as well.

2. Skrill

Skrill, formerly known as Moneybookers, is one of the few true alternatives to PayPal. Though it is global in nature, it’s targeted mainly at U.K. and the other European countries because the merchant fees for these regions are more favorable than for the rest of the world.
Skrill is one of the more popular PayPal alternatives, so if you want to send money to somebody, he or she might have already heard about Skrill, or even have an account. Skrill is also widely accepted by many top websites and service providers, including Skype, eBay and oDesk.
Skrill is easy to use and it allows to transfer your account balance onto a prepaid debit card almost right away.
The fees for personal transfers are very low, though they very from country to country. With a 1% sending fee (capped at a maximum of €10) and no receiving fees, it’s one of the best offers on the market.
With merchants, the fees are much higher, though still acceptable. You can check the fees here. Currently their rates range from 1.4% + £0.20 for U.K. merchants with more than €50,000 monthly sales volume, to 3.9% + €0.35 for non European merchants with monthly sales volume of up to €2,500.

3. Payza

Payza (formerly known as AlertPay) is very similar to the preceeding payment options. It is available in more than 190 countries. It offers generally low fees (though this varies on your location and the type of the transaction) and some of the services are even free. It seems to be the least popular of the PayPal alternatives but still many sites accept it.

Bonus: Local Payment Systems

The availability of local payment services is astonishing, especially for the U.S. Some of the best options include: Stripe, Paymate, Amazon Payments, and Dwolla.
Of all the non-global payment alternatives Stripe is the most promising. Currently they cover the U.S., Canada, U.K., and Ireland but they are also available in beta in another 10 or so countries. At 2.9% + $0.30 per transaction, their fees are similar to PayPal’s. Stripe also has great customization capabilities that might be of interest to developers.
Paymate is a good option for sellers in New Zealand and Australia, though cards from 60-plus countries are also accepted. They have relatively high monthly fees and transaction fees. However, one of the advantages of Paymate is that you can use it to collect payments on eBay.com.au.
Amazon Payments is a good option if you are looking for a credit and debit card processing and an eCommerce platform. It’s an option for U.S. sellers only and it’s fairly pricey for low sales volumes. You can use Amazon Payments on Amazon.com, of course, and some other sites also accept it as a form of payment.
If you are looking for a PayPal alternative mainly for personal payments and you are in the U.S., then Dwolla is probably your best option. With a cost of just $0.25 per transaction and no fees for transactions under $10, it beats all the other systems in terms of fees.
In addition to these systems, there are dozens of payment processors that target particular countries, so do your homework if you only need to sell in-country.