I purchased the Pyramex Mini Ztek glasses that convolushon suggested and got them this week. I found a decent site with good prices and shipping ($1.50/ea and $5 shipping for a few of them):
They fit my kids, but I'm afraid they may grow out of them soon. Unfortunately, my kids have HUGE heads (the littlest one can't fit his head through most shirts!) and the glasses were stretching a bit on my oldest son. I tried them on and they didn't snap, so I guess they're flexible enough to grow with the kids.
Good link on the ear muffs; I will look into those. I was reading reviews on Amazon, and it seems that some of the Peltor muffs work for 6 mo old kids... so I let my oldest try on my ear muffs and they fit a little large on him but not ridiculous.
Any idea how old the kiddie muffs can be used until? Some of them seem marketed to women as well, and I'm guessing my sons' heads will quickly get to the size of a small woman's in a couple years. I'm considering the Peltor Junior, if it works for small adults.