If you've spent long hours outdoors during the pollen season, wash your hair to remove pollen after you come inside. The sticky yellow stuff tends to collect on the hair, making it more likely to fall into your eyes.
If you wake up in the middle of the night with a coughing, sneezing allergy attack, a hot shower may wash off any pollen residues you've collected on your body throughout the day. (You might want to change your pillowcase, too.) It may also help open up your sinuses, at least for a while, making breathing a little easier. The warm water may even help you relax and go back to sleep.
If your eyes are itchy and irritated and you have no access to allergy medicine, rinsing your eyes with cool, clean water may also help soothe them. Although not as effective as an antihistamine, this remedy certainly can't do any harm.