Physics Stack Exchange

This is a fun thing to check out: the Physics Stack Exchange is a crowd-sourced approach to asking (and getting answers to) physics questions. (Hat tip to Chad.) Someone asks a question, others suggest answers, which then get voted up or down depending on how helpful they are perceived to be. It's like an Urban Dictionary for Physics. A quick peek around reveals that there are some really smart physicists answering questions there. See the FAQ for more details about how the system works. Note that it's aimed at "active researchers, academics and students of physics." I know that I'll be forwarding this site to people who email with physics questions. Which means that really I should contribute to answering some of them. You all should too!