One of my all-time favorite sites on the web is the NYTimes.com Learning Center which contains articles, activities, and lesson plans based on current topics. All the lesson plans are geared towards grades 6-12, but the material can be adapted for Adult ESL and Citizenship students.
Lesson plans are linked to current news stories and you can search for past lesson plans by topic. Today's lesson plan focuses on the topic of Immigration and is linked to an article about Day Laborers in New York.
Also of interest is the online almanac This Day in History, which has inspired many warm-up and enrichment activities in my Citizenship class.