This is a tip I read in Canadian Living last week --- and it really works! (It's especially helpful for all my pregnant mommy friends who can't take medication for colds.)
If you feel a tickle in the back of your throat eat some very dark chocolate, one composed of at least 70% cocoa. (I am not making this up.) The chocolate contains an active ingredient called theobromine which suppresses nerve sensitivity in the throat and reduces the urge to cough. According to the article "two ounces of dark chocolate pack the same punch as a dose of strong cough medication".
Ben and I both tried this remedy a few days ago and it totally worked.