There are certain characters that LaTeX has trouble with. One of the main offenders is the tilde (~) symbol. If you include it in plaintext, it disappears in the resulting ps or pdf document. I found out the hard way today when trying to include a URL in a pdf document. However, it gets worse – some of the suggested work arounds do not solve the problem. They create the ~ symbol but the URL still doesn’t work.
It turns out you have to replace the tilde like this:
http://www.unc.edu/~haksaeng/latex-tilde.pdf %Bad http://www.unc.edu/\%7Ehaksaeng/latex-tilde.pdf %Good
That %7E character is legal in LaTeX and represents a tilde in HTML.
To see example LaTeX code for tildes in URLs, check out:
The document the code produces is here: