Neti pots.

[Astreja]

I've used one. It works really well, although it feels like I just went swimming and got water up my nose afterwards.

Definitely use distilled water with one, and either use premixed salt packets or a mixture of sea salt and baking soda (not sure of the ratio). I usually heat the water in a cup in the microwave for about 30 seconds and then pour it into the neti pot.

I don't do this very often, but when my sinuses are really clogged it does help.