I would like to tell about Bitaps.com API advantages.
My first post is very simple - How to accept Bitcoins on your Website.
Create payment address
Main task in processing bitcoin payments is generate and monitoring an unique address for each new user or invoice. Once payment received and confirmed, API server forward bitcoins to main merchant address, cold storage or exchange to foreign currency on markets.

1) customer would like to buy something in your shop. Put items to cart. Click pay via Bitcoins.
2) your shop send your wallet address and callback page URL to us. Shop make query to our server.
3) shop get back new temporary Bitcoin address from us.
4) shop pass this temporary address to customer for payment.
Simple requests:
GET https://bitaps.com/api/create/payment/{ ... /{callback}[?confirmations=0-10&fee_level={high | medium | low}]
Parameters:
{payout_address} Merchant's Bitcoin address where confirmed payments will be transfered
{callback} Urlencoded callback URL
[confirmations] Number of accepted confirmations (optional field, default 3)
[fee_level] Network fee level (optional field, default low)
Response:
Query returns: Address, Payment Code and Invoice.
Address is a Bitcoin address to receive payments.
Payment Code is a private information and merchant should keep it in secret. This Code need for verification of callbacks.
Invoice could be sent to customer and also used for payment form.
You can read more and test your query at https://bitaps.com/api/#Create_payment_address