BHODemon.exe straight up rocks! It checks all of the BHO's on your system and lets you know if they're safe or not. You can get more information here.

Quote:

Think of BHODemon as a guardian for your Internet Explorer browser: it protects you from unknown Browser Helper Objects (BHOs), by letting you enable/disable them individually.? It also monitors your Registry and alerts you when a BHO is installed.? Best of all, BHODemon knows about the most common BHOs - the good ones, and the not-so-good ones!

BHODemon is free, runs in the "tray" area, and works on Windows 95 or later operating systems (in other words, Windows 95, Windows 98, Windows 98SE, Windows ME, Windows NT4, Windows 2000, and Windows XP).