If you like to monitor MySQL, you are going to love this application.

http://ajaxian.com/archives/779

AJAXMyTop is a simple web application that allows you to monitor the currently executed queries on your MySQL server.  It is pretty useful, especially when you are trying to diagnose page loading issues.

If you seek a freeware anti-virus solution for your Windows machine, look no further. Check out ClamWin:
ClamWin Home

Ever wanted to know how much data is stored in a particular folder when browsing your computer? Use FolderSize:

http://foldersize.sourceforge.net/

It also reports file sizes, so you could simply delete the filesize column in Windows Explorer Details View and put ‘Folder Size’ in its place.