Sphinx was originally a pamphlet-sized magazine published by HappenStance Press. Its focus was poetry pamphlet publishing and it ran to twelve paper issues containing features, interviews and poetry chapbook reviews.
Things move on. Sphinx is now web-based.
Features and interviews are posted here online. New ones appear regularly. The main focus continues to be poetry pamphlets, though poetry publishing in general may also be highlighted — or any other topic of interest and relevance.
There is also a comprehensive reviews service for poetry pamphlets. Each publication is appraised by three reviewers (who don't talk to each other and usually don't know each other). All three provide a written review, which is amalgamated into one document. They also submit a rating, based on specific criteria.

The three ratings are amalgamated and published in the form of a Sphinx logo (at the top of the three reviews) with the appropriate number of stripes. The Sphinx logo on this page, for example, has only five. Some pamphlets, however, will have three. Or eight. Or even eight and a half.
Reviews are posted every few months in a new Sphinx issue.
This service is co-ordinated and edited by Helena Nelson.