Add address standardization provider(s)

Currently, CiviCRM only offers the USPS as an address standardization provider. This has two problems:
1) It's obviously US-only
2) The USPS has rules limiting who can use the service.

This is the response I got from the USPS when I tried to sign up for the provided API:

"Thank you for contacting the USPS Internet Customer Care Center. I understand that you would like to access the Address Information API's and I will be happy to assist you.

I apologize; however, the indicated use for the Address Information API's that you submitted does not meet our requirements. The Address API's can only be used in conjunction with USPS Shipping Services and is not intended for cleansing databases or batch processing.

For a fee, the USPS offers the AMS API CD as an alternative, which has all the addressing needs on it that would have been provided through the Addressing API. The Address Matching System Application Programming Interface allows the customer to place the data in one location, on one server, and develop on one platform. If you wish to develop on multiple platforms, or develop software for resale, there are additional charges. You will receive an update via CD-ROM every other month. You may also request to receive monthly CD-ROM updates for additional charges.

If you're interested in ZIP Code information, various ZIP Code products are available on CD-ROM on an annual subscription basis with monthly updates."

In light of those two major problems, the existing provider is unusable for a large portion of the CiviCRM user base. We need to get at least one additional address standardization provider (maybe Google?) built into CiviCRM to have usable data.