I’m very happy to know about the Don Martin Dictionary, having grown up on a steady diet of Don Martin sound effects.
(Both LanguageLog and, appropriately, BoingBoing linked to this.)
UPDATE: This is a good one, can you guess what it is?
SHIF-SHAF SHABAMP MAMP SHOMPAH-BOMBAH DIMPAH MIMPAH FOMP-DABOMP! GADIFF-GADIFF GADAFF GADAFF GASMITCH GASMATCH KABOFF FAPADDA DAPADDA SWIPADDA DIPADDA FAP SPMAP GAMOP