The Delaydelus
Sampler + Delay instrument by Dr. Bleep and Daedelus.
http://bleeplabs.com/delaydelus
To upload the defualt samples into the serial flash, use the "upload x.in" in order, then uplad delaydelus_v29.ino. This is the easiest, hackiest way of getting data into the s25_fl without some kind of complicated serial communication.
If you're just wanting the newest version, only upload delaydelus_v29.ino.