Links to SDSS data release papers. The EDR paper contains infromation common to all data releases, while the others describe changes relative the prior release.
The paper is essential reading for anyone wanting to use the SDSS for science, describing not just the EDR but all features common to all data releases.
Provides http and rsync access to fits and ASCII files produced by the SDSS data processing pipelines. I recommend the DAS for downloading data for offline processing, while the CAS is more appropriate for online processing.
The homepage of the Sloan Digital Sky Survey includes a very high level description, links to SDSS technical, management, and educational pages, and news items.