Sometimes, i create basslines out of all different sounds. Say you have a long, steady guitar sound. Go to your param's screen from your program screen (hit the pad you want to adjust)..... and tune the sample way down, as well as turn the filter way down.... maybe even to 0 depending on the sound. Then, either resample, or record it and resample it manually into your MPC, and repeat the process until you achieve the desired results.
Basslines are so easy to manipulate that once you have a few quality samples, you can freak 'em endlessly.....
"And Rodney King...... Ain't NEVER felt the beat like this"