There are a number of useful sources on the web for background on Latin American affairs and U.S. policy in the region.

Analysis:

NACLA Report on the Americas
The most widely read English-language magazine on Latin America, published by the North American Congress on Latin America since 1967.

NACLA Archives
The complete archives, from the NACLA Newsletter of 1967 to the NACLA Report

Americas Program
The CIP Americas Program, based in Mexico City, is a network of policy analysts throughout the hemisphere that explores and promotes citizen-based policy options for development, trade, and international relations in the Americas. The Americas Program provides timely information and analysis in English, Spanish and Portuguese to create a North-South dialogue based on the principles of sustainable development and environmental protection, equitable economic development, multilateralism, and respect for human rights.

Center on Hemispheric Affairs
An independent, non-profit research and information organization, established to promote the common interests of the hemisphere, raise the visibility of regional affairs and increase the importance of the inter-American relationship, as well as encourage the formulation of rational and constructive U.S. policies towards Latin America.

Washington Office on Latin America
Founded in 1974 by a coalition of religious and civic leaders, WOLA promotes human rights, democracy and social and economic justice in Latin America and the Caribbean. WOLA also facilitates dialogue between governmental and nongovernmental actors, monitors the impact of policies and programs of governments and international organizations, and promotes alternatives through reporting, education, training and advocacy.

News:

Global Information Network
A non-profit news and world media operation, is the largest distributor of Developing World news services.

InterPress Service Latin America
Continuously updated news service covering Latin America and global affairs.

Latinamerica press
Latinamerica Press/Noticias Aliadas website, which provides independent news, analysis and information about Latin America.

Upside Down World
Upside Down World is an online magazine covering activism and politics in Latin America. Founded in 2003, it is made up of work from writers, activists, artists and regular citizens from around the globe who are interested in flipping the world upside down...or right side up.

Z Magazine
Z Magazine's extensive website. Has links, an archive of back issues /articles, activist resources, etc.

Journalism

American Journalism Review American Journalism Review is a national magazine that covers all aspects of print, television, radio and online media.

Columbia Journalism Review Columbia Journalism Review is a magazine that examines day-to-day press performance as well as the forces that affect that performance.

International Reporting Project The International Reporting Project is designed to educate U.S. journalists about global issues and to increase and improve the coverage of international topics in the U.S. news media.

Knight Center for Journalism in the Americas, University of Texas
Maintains a news monitoring service on news about journalism in the Americas.

Media Alliance Media Alliance is a media resource and advocacy center for media workers, non-profit organizations, and social justice activists. Our mission is excellence, ethics, diversity, and accountability in all aspects of the media in the interests of peace, justice, and social responsibility.

Project Censored Project Censored is a media research group out of Sonoma State University which tracks the news published in independent journals and newsletters. From these, Project Censored compiles an annual list of 25 news stories of social significance that have been overlooked, under-reported or self-censored by the country's major national news media.

Analysis from other sources:

You can find other groups' analysis of media coverage here.