I've been very fortunate recently. I was invited into an ad-swap group on Skype by a friend and associate, Jason Anderson. It's done my listbuilding no end of good!
I was given a start off on a list by Jason and his buddy Bruno, and they got me about 300 in one big mailing, just as a favor.
Then Jason invited me into the group. Since then it's been plain sailing!
Getting swaps at the start was a little hap-hazard, but I was soon able to get daily bookings....