Does anyone know of somewhere on the Net where I can download WAV files of those "arena calls" they play at NBA games (like the DA-DA-DA-DA-DA-DA-CHAAARRRGE! effect for example)?

You might have checked this already, and it doesn''t actually answer your question, but my local library has a large collection of sound effects CDs and LPs that are intended for film or video use. They even have a couple of sports-events CDs. These make great sounds for video games. Maybe the library near your has some, too.