The Resonant Core blog has a post today with a selection of tips and techniques you can use to help build secure applications in PHP, preventing several of the most common issues (several as mentioned in the OWASP Top 10).
There are but two causes for the unintentional creation of insecure web applications: A lack of knowledge about security [and] bad development habits. Developers who don't know about the risks involved with writing a widget a certain way are unlikely to make the secure choice. Thanks to the work of MITRE and OWASP, the most common vulnerabilities (and their consequences) are widely known and accessible. However, when teams are under pressure to meet a tight deadline, bad habits and insecure development practices may still emerge.
Most of the examples (at least the solutions) center around a framework they've created (Tuner) but the concepts are all there and could be adapted to other tools easily. They talk about the "pain" that can come with secure coding and how the right tools can make it much easier for the developer. He talks about how the framework offers a better database interface based on PDO and prepared statements to prevent SQL injection issues (with examples for each of the CRUD operations). He also shares a list of pre-existing PHP libraries that can help make the rest of you application secure too including:
He also mentions a PHP extension that adds in scrypt support, another option for hashing strings and passwords as an alternative to bcrypt.