Economics
University of Houston Department of Economics
IPUMS: One of the best resources for demographic data, including micro-level Census and CPS
NBER: Latest working papers in economics research
ICPSR: An extensive collection of data from a myriad of sources and topics
UCLA Stata Help Documents/Links: A site to help you get started with Stata
Stata ListServ: Join Stata listserv to ask any technical questions dealing with Stata; very fast response time
Microeconometrics: Methods and Applications (Cameron & Trivedi): A great, hands-on textbook for any empirical microeconomist; here is an accompanying Stata guide that is just as helpful (Microeconometrics Using Stata, Revised Edition)
LaTeX on Mac: TeX User Group for Mac users
Stata on a Mac: Blog for Stata users on a Mac
Dropbox: An essential tool for file sharing with co-authors or across multiple computers
Sites with Economic Content
New York Times: One of my favorite places to find research topics
New York Times Economix Blog: Great discussion of every day economics
EconPhD.net: Good resources for graduate students in economics
PhDComics: Funny and poignant observations on the life of graduate students