Google Safe Browsing API - Google has put together a really cool API that allows developers to query their database of suspected malware and phishing sites.
Lets Go Phishing - PhishTank (http://www.phishtank.com/) is a service that allows you to submit suspected phishing sites and tracks their status. With an open API, PhishTank even lets you write tools to query their data.
Here's a Vexing Question - There have been many studies on why phishing attacks are such a problem.