360 Works' plug-in is great and works well, but I found it's a little too simple for our clients. The main problem we encountered was there wasn't enough error capturing. There's also the problem of storing credit card numbers within a database, security concerns, PCI-DSS compliance, etc.
X-Charge (http://www.x-charge.com/) also has a really simple-to-use FileMaker plug-in for processing credit cards if you're looking for options. Using X-Charge you don't actually store credit card numbers but an alias of the credit card number.
Depending on your needs, though, it may also be worthwhile to consider using SmartPill (http://www.scodigo.com/products/smartpill-php) like we do to use PHP to connect directly to both Authorize.net and X-Charge's systems using their API.
Here is a small blub on why we prefer X-Charge / PHP.