Document based RM

I understand the benefits of requirements management, and my company develops our software using requirements documents. My question is how many others out there actively use RM documents?
I have seen a lot of database tools for RM, but not manydoucment based tools. We looked at Rational’s RequisitePro but found it to be too expensive / bulky for our needs. What do those of you who keep RM docs use for tracking and relating project requirements?