Another Debt Question!

Has anyone dealt with a legit debt relief/debt management company?

I have ~18k in credit card debt, and make less than $20k/year. I'm working on selling everything I don't need, but it's still going to be a slog to pay it off and start over. I'm not behind on anything, and unless business bottoms out completely I should be floating for the foreseeable future.
I was thinking about contacting a company that the NFCC recommends to speed the process of paying it all off - but I'm not sure how much I'd potentially save in exchange for the hit on my credit score.

I don't know a good one, but I had a not-great experience with The Credit Counseling Foundation (based in Florida). They charged extra to make your payments electronically and failed to make payments on time several times in the 3 years I used them, negatively impacting my credit rating even more. They did get the interest rates lowered on several cards, but with the up-front payment they required and the additional fees they charged ($35/month service fee), I really don't think they saved me any money.

If you are thinking about trying to do it yourself with a consolidation loan to pay things off, I can highly recommend Prosper.com.