Thanks all!
I'm going to go get some new socks, and also some of that runners glide stuff, and hopefully this will help.
Maria - I definately always wear clean socks. My feet sweat a LOT when I work out, and repeating socks isn't even an option.
Icon - I used to run once a week (for 3 miles) and then 2 other times for 1 mile each, but never got any blisters. Now I try and do 3 miles 2x a week and 5 miles 1x a week, and I find I'm getting blisters every time. So yes, I've increased, but my feet are even reacting to what they're used to (if that makes sense).
Jen - fortunately I have lots of moleskin left from my hike