I use mine for the usual things like digging around in my car at night, especially in the trunk where the built-in light isn't very useful at times. Some people said they use theirs for reading in bed, but there are times when I've used mine on low-mode or red mode in bed for other night time activities... sometimes it helps to see exactly what you're doing, but without the bright overhead lights or lamps.
My favorite use is for night hiking! As much as I love to hike during the day, I love it even more at night. I'm very fortunate to have hiking groups here locally that do regular night time hikes year round - last night we did 6.1 miles on the MST with temps in the low 30s. It was perfect for hiking! The moon was out, the sky was clear and full of stars. Tonight we did 3.5 miles, much more tame this time though, on basically the equivalent of a greenway. Temps were in the 40s. Good exercise, but not nearly as much fun.
My primary headlamp is a Black Diamond Cosmo - it has two white modes: spot and flood, both with continuously variable dimming and a single red mode. It puts out 70 lumens max, doesn't have great throw but works extremely well for my purposes. I keep a handheld flashlight in a holster attached to my backpack strap for when I want more throw. It runs off three AAA's and I get great runtimes! Manufacturer claims 43 hours on high...