I believe you will want to use the 'raw_input' function to do this. Here is an example:import arcpy, os
from arcpy import env
env.workspace = r"C:\temp\python\test.gdb"
env.overwriteOutput = 1
county = raw_input("Please type either WARREN, WASHINGTON, OR ESSEX: ")
key = raw_input("Please type the Parcel ID: ")
# User selects COUNTY and then Print Key value, Select by Attribute tool runs
arcpy.MakeFeatureLayer_management("Parcels", "Parcels_feat")
arcpy.SelectLayerByAttribute_management("Parcels_feat", "NEW_SELECTION", "COUNTY = " + "'" + county + "'")
arcpy.SelectLayerByAttribute_management("Parcels_feat", "NEW_SELECTION", "PARCELS_ID = " + key)
arcpy.CopyFeatures_management("Parcels_feat", "Parcels_Selection")
print "Executed succesfully"
This will prompt the user for a county name and a parcel ID.