You can of course modify the recordset after you have the results page created, but I understand the desire to have more than one filter.
We have thought about this a good bit, and once you add the ability to have multiple, then many would ask about the ability to have AND as well as OR conditions on those filters, as well as the potential for grouping some filters with AND and some with ORs and then combining those together some how. From what we've been able to think up, it's not a really easy problem to solve within Dreamweaver user interfaces.
That being said, what type(s) of filters would you be interested in?