This is a PHP library allowing you to send any form input through a spamfilter. Currently spamprobe is the only one supported. The sample application was guestbook, which is now outdated. It comes with a RESTAPI but can also be included directly into any PHP project. Training of the filter is included. After some time it's getting very reliable.
phleackr is a PHP binding for the Flickr API, using the XML-RPC format and thought to be compatible with PHP4 and PHP5, while avoiding the need for PEAR packages. in the future it will also support the REST format.