We would like users to specify certain pages an action can occur on. There are two conventional ways:
textarea with some delimiter (whitespace, commas) between the urls. This is OK since usually the users are webmasters and proficient enough with computers.
Separate Inputs: Plus button allows to add another input, Remove button is shown on every input on hover, clicking on the last and empty input creates another one. This is complicated and makes the user click or press tab to move between inputs.
Those are the general solutions I'm aware of. Any better ones?