I have some significant debt, and I've put some of the project expenses on 0% APR credit cards to bring it to completion, lowering my credit rating.

Credit card?

Can you by with zero percent introductory rate credit cards and cash flow payments! 

I go so far as to give any of my clients my Lawyers business card any time they say “I’m going to sue you.”

they owe everyone, like utilities, cellphone, credit cards etc.

You could attach picture of the property, the Lease, manage account balance easy, add/remove fees, and tenant may use the Credit Card for rent payment if they have emergency (Cozy will charge them some fee).  

I'm basically looking for a site that I could direct my tenants to and they can use their debit card to pay rent.

@Carlos Velez - beyond the options already mentioned, pull out a zero interest credit card and cash the personal check they give you.

He said he would not use a credit card, and wanted to use a certified check.Please share your thoughts. 

Currently in 50k debt (carnote, IRS, loans and credit cards).