I had to work on a movie and set up an animation for a fly.
I came out with this expression. it's a small tip but it works. Just try to assign to a little sphere or to your model and the game is over. It works in a semi-random way. I think you'll love. I've tried also any others values to enhance the result and every time is a nice game.
myfly.translateX = noise(frame/12)9sin(time)*7+rand(time/5);
myfly.translateZ = noise(time)8cos(time)*12+rand(2);
myfly.translateY = noise(frame/10)7cos(time)*9+rand(0.65);
or you can try also:
myfly.translateX = noise(2-time*3)2cos(time)*3+rand(0.12)-8;
myfly.translateY = noise(time*2)5sin(time)*3+rand(0.25);
myfly.translateZ = noise(2-time/2)5sin(time)*6+rand(0.15)+2;
have a nice day
Gianlucas