I did some contracting work for a company last year, and the total
amount they paid me was less than $600, so they did not send me a
1099-MISC.  Someone told me that since I didn't receive a 1099-MISC, I
wouldn't have to report the income on my tax return.  I'm skeptical of
that, and in fact have seen some people on the internet say that you
must still report all income even if you didn't receive a 1099-MISC. 
Are there any reputable web sites that answer this question?

This should be helpful:

http://www.alllaw.com/articles/tax/article4.asp

I found the "all income from whatever source derived" reference to be
useful, and clearly the following line answers the question:

"Even though a business needs to pay you a minimum of $600 before they
are required to submit a 1099-MISC, you are required to report all the
income you receive from all sources, even if it is less than $600."

I also wondered why that page didn't show up in my searches, and I
discovered that I needed to use the dollar sign ("less than $600"
instead of "less than 600").  It appears to be an HTML entity issue.

Thank you!