Dragg the following two links to your browser's toolbar (tested with Firefox 1.5 and IE 6) :
log49 = ;//log49 is global variable.
var num = 1;
log49.push('num = '+num); // log the state of num
num = num+1;
log49.push('second num ='+num); // again.
Then the two bookmarklets let you reset or view the log in runtime.
49.cl lets you reset the log by clearing the list stored in the global variable log49.
49.sh shows you the log by joining and alerting the value of log49.