Google Specific

• Google Calendar - I started using Google Calendar for my personal schedule about a year ago and just a couple months ago moved my World History calendar away from the html version I had used for years to Google Calendar. Now I can easily and quickly make changes to my calendar. At my school we are working to get more teachers to use this feature and hopefully students/parents will be able to subscribe to all of their teacher's calendars.
  
  
• Google Docs - Don't need all the features of Office, try Google Docs. Current you can create and edit spreadsheets, text documents, and presentations. Plus it offers the ability to easily collaborate on any project!
  
  
• Custom Search Engine - This is one of the more powerful tools that Google provides. Now you can select the sites or domains that you want your students to search. You don't have to worry about students searching the WHOLE web - great for younger students and when you want to direct your students to more specific content. Best of all, it still looks like Google.
  
  
• Google Square - A different way to provide some specific sites.
  
  
• Picasa Web Albums - This is Google's version of the much better Flickr (now owned by Yahoo). The place Picasa trumps Flickr is that it isn't blocked by my district. So anything I want my students to have access to, I use Picasa.  If you use Google Sites, adding a slide show is very easy.
  

Others

• Docstoc - a Flash based document viewer
  Pros: Able to view formatting online, able to embed in your web site (Example)
  Cons: Not everyone has Flash
  
  
• Slideshare - Upload all of your PowerPoints and share them on this YouTube-like site. You can also attach an mp3 to them.
  
  
• TeacherTube or SchoolTube - these sites are designated for educational materials. (You can download YouTube videos using this site: Zamzar.com)