Ben some questions:
1). In your example you have "balance > 100" as the filter. Would your users just have 1 field (like balance) and you want them to be able to store diff. amounts (100, 500, 0, etc.) or do you want them to be able to also filter on State = 'CT'?
2). A single filter or a combination with AND / OR?
3). How do you expect your users to enter the filters? Will they know all of the attribute names or do you want to give them a sort of GUI for them to pick the attribute, operator and condition?
Bruce