Dragg the following two links to your browser's toolbar (tested with Firefox 1.5 and IE 6) :
49.cl
49.sh

When you are writing some javascript embedded in a webpage and you want to debug your code, this gives you way to log things without alerting them. 

Example :

// part of embedded javascript code
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.