Conditional Approvals

When setting up approvals I can only select from a handful of pre-defined conditions built into the tool. Since I can't define my own conditions, I can't create the approval workflow I need.

To make Approvals more flexible and useful, please allow the admin to create his own conditions based on custom field values and logical tests. For example:

If
Custom Field1 value = "XYZ"
Then
Approval path X

The interface should be a flexible as possible allowing the admin to select any base or custom field and define any logical Boolean comparison.