WordNet (r) 3.0 (2006):

scratch pad
    n 1: pad for preliminary or hasty writing or notes or sketches
         etc; "scribbling block" is a British term [syn: scratch
         pad, scratch paper, scribbling block]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "scratch pad":
   Domesday Book, account book, address book, adversaria, album,
   annual, appointment calendar, appointment schedule, blankbook,
   blotter, calendar, cashbook, catalog, classified catalog,
   commonplace book, court calendar, daybook, desk calendar, diary,
   diptych, docket, engagement book, journal, ledger, log, logbook,
   loose-leaf notebook, memo book, memorandum book, memory book,
   notebook, pad, petty cashbook, pocket notebook, pocketbook,
   police blotter, scrapbook, spiral notebook, table, tablet,
   triptych, workbook, writing tablet, yearbook