Sweat in Eyes

I use a Halo Headband. It works pretty good, but I have had those really hot days where I sweat a lot more than usual and will have a drop or two start to roll down my nose. I just stop and wring it out which will hold of the sweat for another 45 minutes or so.
+1 on the halo headband.

On the cheap I have used a rolled up paper towel tucked neatly in the front of the helmet.

I also carry a water bottle with pure H20. A quick shot in the eyes gets rid of the sting of sweat.