A variation on the uniform wanderer with the addition that you can touch the primitive in order to toggle the wandering.

wanderer_uniform.lsl

///////////////////////////////////////////////////////////////////////////
//  Copyright (C) Wizardry and Steamworks 2014 - License: GNU GPLv3      //
//  Please see: http://www.gnu.org/licenses/gpl.html for legal details,  //
//  rights of fair usage, the disclaimer and warranty conditions.        //
///////////////////////////////////////////////////////////////////////////
 
///////////////////////////////////////////////////////////////////////////
//    Copyright (C) 2013 Wizardry and Steamworks - License: GNU GPLv3    //
///////////////////////////////////////////////////////////////////////////
vector wasCirclePoint(float radius) {
    float x = llPow(-1, 1 + (integer) llFrand(2)) * llFrand(radius*2);
    float y = llPow(-1, 1 + (integer) llFrand(2)) * llFrand(radius*2);
    if(llPow(x,2) + llPow(y,2) <= llPow(radius,2))
        return <x, y, 0>;
    return wasCirclePoint(radius);
}
 
moveTo(vector position) {
    llTargetRemove(targetID);
    targetID = llTarget(position, .8);
    llLookAt(position, .6, .6);
    llMoveToTarget(position, dampening);    
}
 
// track targets
integer targetID = 0;
// dampening of movement
float dampening = 10;
// stray from origin
float radius = 5;
// the origin of the movement
vector origin = ZERO_VECTOR;
 
default {
    state_entry() {
        llOwnerSay("movement off");
        // set the origin to the current position
        origin = llGetPos();
        // stop all physics
        llSetStatus(STATUS_PHYSICS|STATUS_BLOCK_GRAB, FALSE);
        llVolumeDetect(FALSE);
    }
    touch_start(integer num) {
        state on;
    }
}
 
state on {
    state_entry() {
        llOwnerSay("movement on");
        // set the origin to the current position
        origin = llGetPos();
        // start physics
        llSetStatus(STATUS_PHYSICS|STATUS_BLOCK_GRAB, TRUE);
        // pass through solids but detect collision
        llVolumeDetect(TRUE);
        moveTo(origin + wasCirclePoint(radius));
    }
    touch_start(integer num) {
        state default;
    }
    at_target(integer tnum, vector targetpos, vector ourpos) {
        moveTo(origin + wasCirclePoint(radius));
    }
    collision_start(integer num) {
        moveTo(origin + wasCirclePoint(radius));
    }
    on_rez(integer num) {
        // set the origin to the current position
        origin = llGetPos();
        // stop all physics
        llSetStatus(STATUS_PHYSICS|STATUS_BLOCK_GRAB, FALSE);
        llVolumeDetect(FALSE);
    }
}