Natural Bug Repellents?

Today we had another adventure. After a false start that included picking a forest preserve that didn't really have much in the way of hiking, we found a secluded little path to stroll along. Chickie was a trooper, picking dandelions and sticks until the very end, when she became oh so pokey! Daddy scooped her up and we finished the very end of the hike. She wanted to walk to the car, and that is when I noticed it...A TICK! in.her.hair. Luckily it was just crawling there and hadn't burrowed in, but there was a tick on my baby! It doesn't make for a happy mama when possible disease carrying, head burying little critters are crawling on your little girl! We decided to head home and give ourselves a good once over when I felt a little tickle on my forehead. Yup, you guessed it! A tick was crawling out of my hair. I still have the heebie jeebies!
Now I realize that ticks are part of the great outdoors. And despite the fact that I am still squirming, even after a thorough inspection of all three of us, showers and every stitch of clothing we were wearing being washed in super hot water, we have no intention of giving up our adventures. But our very mild spring weather will soon be giving way to full fledged summer, which means in order to comfortably hike, we will have to avoid the heat of the day and hit the forest preserves when mosquitoes are out in force. So what I am wondering is this...Do you have any good bug repellent tips? Preferably natural ones. While I recognize that covering ourselves from head to toe in DEET may sufficiently repel the bugs, hiking in a cloud of toxic chemicals kinda ruins the whole filling our lungs with fresh air thing.

So lay them on me folks...your best natural bug repellent tips!