The API Explorer is great! I can't wait to see how much further this new feature can go.
One small thing I think would help is to allow BLANK parameter values. I see sometimes in an API that blank parameter value will keep the parameter active, but won't manipulate the results until a value is put in.
Right now, when a parameter value is left blank, a Zero is automatically entered, which seems to break the feed for several API's I've tried.