Saw another few of these today and thought I'd collect related links somewhere. Comment with any that have been useful to you!

• T. Tao on career and writing
• S. Billey's advice collection
• I. Pak's blog
• C. Aten's 'one pager' for all stages in math
• University of michigan grad advice (note: use the dropdown menu at the top; links in main content are broken atm)
• ICERM professional development materials
• AMS profiles of women mathematicians
• I. Musson's LGBT resources links
• Academic Stack exchange on postdocs

not math specific, but grad/research related:

• thesis whisperer
• care and maintenance of your advisor
• (comp-sci inclined) the huge advice collection maintained by Tao Xie and Yuan Xie (I surely duplicate some of their items)