Useful mathematics links:  

• The Number Theory Web
• MathSciNet
• ArXiv search
• William Stein's Modular Forms Database
• William Stein's index of scanned papers
• Gottingen's Inventiones scans (and other journals)
• Quebec-Vermont Number Theory Seminar 2004-05

Direct links to some number theorists' lists of papers

• Laurent Berger
• Christophe Breuil
• Kevin Buzzard
• Frank Calegari
• Henri Darmon
• Jordan Ellenberg
• Matt Emerton
• Kiran Kedlaya
• Chandrashekhar Khare
• Mark Kisin
• Rob Pollack
• Ken Ribet
• Rene Schoof
• William Stein
• Richard Taylor
• Tom Weston