The website Beyond the Perf and mobile app from the USPS features the postage stamp issues of the years 2009 through 2013. Each issue has information on the background of the stamp and series, date of issue, designer, etc. Quite a nice accumulation of information in one spot for the U.S. collector. A mobile app for each year is also available free.
An online extension of the USA Philatelic catalog, Beyond the Perf was developed to bring you in-depth information about stamps, cancellations, and related events.