Whether any homemade cold remedies actually work is up for debate, but these will definitely make you less miserable. Also great for bringing to sick friends (they'll love you forever).
Lemon, Ginger & Honey Flu Remedy
Source: instructables.com
This is the classic combo for a reason; even if it doesn't cure you, it will make your mouth happy. Instructions here.
Flu Buster Clementine Creamsicle Smoothie
Source: ohsheglows.com