BigBiller by Top Echelon has worked well for us.
Hi Julie - I might want to check out SmartRecruiters - a Free ATS, unlimited usage/storage. Don't want to be promotional, but upon your description it could meet your need. Fairly new, in beta - without bell and whistle but the technology is completely for free.
Just check it out at www.smartrecruiters.com and if any questions/feedback, let me know.