Debugging javascript in Internet Explorer is still a pain unless you have fancy tools like MS Studio installed etc. YUI logger is quite good for debugging but the problem with that is that you need to have all the required CSS and JS files in your source code and then you have to worry about removing all that before you roll your code out in production.
This is resolved by adding YUI Logger to your page using javascript via a bookmarklet which saves you the botheration of adding and removing code to create a logger
Click on the link to invoke the logger, or drag it to your bookmarks folder to create a bookmarklet Load Logger
This obviously wont get triggered on page load, so if you want to watch logs from events that happen without user action then you either have to be super quick or just find a better way to do that. If you have a better way to invoke a bookmarklet from your code do drop me a note.