[btbuildem]

Whatever buddy. Make something of value and people will pay you for it. Or make useless amusements, and depend on ad revenue.

[j2kun]

There are ways to get the best of both worlds. XKCD is free and ad-free (and a useless amusement, as are most things people want to pay money for).

[greenyoda]

xkcd had developed enough of a following that its author can make money by selling xkcd-branded merchandise (http://store.xkcd.com).