My client has an older version of the Yardi Software, which they use for handling rentals. It would have to handle a number of companies of course and have some way to keep track of rentals with codes for tenants within companies, or maybe as accounts receivable with recurring charges. Do you know of any systems that might work for them?
I would also like to recommend Handteq. They provide a very cost effect way for managing tenants, accounts, and billing.