Russian Language Mentor - excellent and fun site with helpful language and culture modules. Unfortunately, the self-correcting exercises only work properly on a PC (they provide incorrect answers on a Mac).
Стихия - great collection of literary works by classic and contemporary Russian writers (in Russian).
News, Newspapers, and Magazines
Новости недели на упрощённом русском языке - delivers a survey of the previous week's news in simplified standard Russian. Listeners of Voice of America's "Special English" broadcasts will recognize the slightly slower rate of speech and textual redundancy which characterize these webcasts. Includes exercises and transcripts. The broadcasts are archived, but still a wonderful resource for second- and third-year students.
Эхо Москвы - serious news and culture radio station in Moscow (closest thing to NPR in Russia)
BBC Russian - BBC audio programs and articles in Russian
Meduza - headquartered in Estonia to avoid pressures on media freedoms, covers news from Russia and the former Soviet Union in both Russian and English.