Compete API wrapper
After taking a look at the Compete service I thought I could make use of the API they offer. Lacking a PHP wrapper for it though I wrote my own.
Soon after releasing that I was contacted by Hiroki Akimoto who had a proposal at PEAR for a compete API wrapper. We decided to combine efforts and produce the best wrapper we could. As such I recommend you use the PEAR package.
If for some reason you want to use my original code you can download the zip archive.
Both my original code and the PEAR package are written for PHP5. If you're still using PHP4 it might be time to move on.