There are many paths to U.S. permanent residency, including:
USCIS - Green Card Eligibility
USCIS - Visa Availability and Priority Dates
USCIS - Immigration Medical Exams
USCIS - Standard Operating Procedures for Adjudication of I-485 Adjustment of Status Applications (PDF)
USCIS Update - USCIS to Issue Two-Year Employment Authorization Documents - June 12, 2008 (PDF)
USCIS Announces Revised Procedures for Adjustment of Status Applications - July 17, 2007 (PDF)
USCIS Memo - Legal and Discretionary Analysis for Adjudication - May 3, 2006 (PDF)
USCIS - Other Ways to Get a Green Card
USCIS - Resources for New Immigrants
USCIS Guide - What Are My Responsibilities as a Permanent Resident? (PDF)
USCIS - After a Green Card is Granted
USCIS - Maintaining Permanent Residence
USCIS - International Travel as a Permanent Resident
USCIS Guide - How Do I Get a Re-Entry Permit? (PDF)
USCIS Guide - How Do I Renew or Replace My Permanent Resident Card? (PDF)
DHS to Green Card Holders: Fingerprints and Photos, Please - WIRED - December 23, 2008
Immigrants Try to Keep Up with Green Card Yo-Yo - All Things Considered - July 18, 2007 (link to audio)
A Green Light on the Road to Green Cards - BusinessWeek - July 18, 2007
After Protest, U.S. to Take Green-Card Applications - Washington Post - July 18, 2007
Immigrant Processors Fall Behind - Washington Post - Jan. 4, 2007