I found this compilation on Tips for applying to Graduate Programs (mostly US) by Jennie Miller at Yale University quite useful. Please add your own links that you found useful for the benefit of our members.

http://jenniemiller.weebly.com/tips-on-applying-to-graduate-programs.html

• Jennie's tips on how to apply to graduate school - Advice from my own experience
• Some Modest Advice for Graduate Students - Motivation from Dr. Sterns at Yale EEB to take with a grain of salt
  
• Reply to Sterns: Some Acynical Advice for Graduate Students - More (positive) motivation from Dr. Huey
  
• The Graduate School Essay I Wish I Had Written - A sample application essay by Dr. Thomson at the Claremont Colleges
• Professor Singer's Advice to Prospective Students - General tips from a professor at the University of Texas
• On Graduate Studies in the Biological Sciences - An overview of the process for biology programs in general
• Sell Yourself: Guidance for Developing Your Personal Statement for Graduate School Applications - Tricks on writing your application essays and representing yourself well