www.nextissue.com is a great service! Get access to over 100 magazines includes about a year of back issues for $10/month. A terrific edition to my iPad!
UPDATE: Three years later and I’m still using this app which is now called Texture. Apple named it one of the best apps of 2016 and it has a 4.5 rating in the app store.
They now have a highlights feature that alerts you to the most popular articles read across all magazines. They now have over 200 magazines available but to get the most out of Texture it’s a little more at $15/month.