Unfortunately, the answer is no, at least not in most cases.
These debt consolidation/negotiation/management places make a LOT of money off of people while trashing their credit beyond belief. They charge outrageous fees, and even the ones who claim to be 'non-profit' have these very convenient 'donations'.. which turn out to be MANDATORY... some donation, huh ?
If you decide to go this route you must be VERY careful and VERY diligent. You basically have to go thru their terms and conditions with a fine-toothed comb and monitor them very closely. These places are bad for routinely making payments late, NOT making payments, not making payments large enough to make any headway or incur more finance charges. Some places will hold ALL your money until an account is near charge-off and then try to settle (without any negotiation on your credit report entries, I might add !). At that point, your credit is totally trashed, you might as well file for bankruptcy. They'll probably also tell you that it'll take 5-7 years to pay off your debts in their program.. and those estimates don't always turn out well either.
You might want to read about these kinds of places here:
http://www.creditinfocenter.com/debt/DebtConsolCompanies.shtml
Its not impossible to find one that works, you just have to be extremely careful and monitor everything that's goes on.
There's also not guarantee that all your creditors will participate, they don't have to.
I've seen so many horror stories on this board and others that I dont' think I'd ever use one of these places. There are some who've had good experiences, so they do work, but they seem to be few and far between.