Internet Explorer has a nasty habit of allowing so-called Browser Helper Objects (or BHOs) to install themselves into IE. Some BHOs are helpful, like the Google Toolbar, but others (especially those planted by viruses or spyware) can be malicious and harmful.
BHODemon gives you a quick look at the BHOs installed on your PC, tells you whether a specific BHO is known to be safe or harmful, and gives you the ability to enable or disable individual BHOs with a single mouse click.