The Directory of Open Access Journals now includes all PLoS Journals.
Here's an excerpt from the announcement:
Finally, after saying: "It's coming" for almost a year, DOAJ has added the entire PLoS catalogue to DOAJ. A total of 182,500 articles were added and the harvester is set to go out and collect new articles at 5.30am every morning. The harvester collects the metadata from Europe PMC.