Ping Pong is a free sample-based instrument for Native Instrument Kontakt (version 3 or 4).
I tried to program a sound similar to a ping pong ball bouncing on a table, finding later that it was more intersting to alter the sound with few effects like delay, reverb and a band-pass filter (with the chance to control their amounts via velocity). This version come with 5 different effects presets directly available from the performance view in Kontakt.