Here are some of my favorite sites for today:
CAIUMoodle - The Moodle installation at CAIU
Joomla - a content management system
BlogLines - an online aggregator for RSS and XML feeds
NetVibes - a great choice for a home page
Writely - collaborate on Word docs
Flickr - powerful social photography site
Del.icio.us - social bookmarking
Skype - free voice over Internet phone
GoogleEarth - throw away your geography books
ThinkFreeOffice - Why buy Office when you can access it from the web?
Google Notebook - maybe the best little program you'll never use
Take Notes - a great collection of links to sites that let you store your notes online
Tipline - My tips :-)