I had one instance where I considered taking a client through collections - and decided the negative energy necessary to do so (and the time) wasn't worth it to me. I let it go and beefed up my payment policies/deposit requests for new clients.

I did look into Dunn and Bradstreet as an option - they have a few 'a la carte' options for small business owners to use to try to recover monies owed.

I have read a lot of stories on line of other freelancers who did pursue collections and all basically said it was a real drain. I would only go that route for invoices of a substantial amount - but again, would work to avoid it with deposits and ironclad agreements from the start.