For Education

Evernote: awesome app and site for keeping every type of note available, such as typed, audio, photos, links. In conjunction with my iPhone, its essential for me to keep all my projects, meetings, ideas, etc organized ans synced.
Google Groups: great for connect students to a common project. For example, I used it for my Geometry House design project. Students could share ideas and designs. Plus, I could easiyly make pages for them to reference on the same page that they were using to work.
Google Calendar: Not only can I add, delete, and edit on my phone, its linked to my website, so that students, athletes, or others can see it in real time. For example, if I change a test date, add a Campus TV episode, cancel a meeting, modify the leave time ofr a meet. I just use the google API to make it happen. Plus when I check my email on a computer, the calendar is one click away.
Twitter:I know, I know. Some people just hate it, but I love it. It publishes short burst of text (or status) and/ or a pic. It sually a bit random, but students can see that I am an actual real person and ont actually live in my classroom (though, it feels like I do). The other part I like is that it is completely open for anyone to read, unlike Facebook. All my activity is public, so anyone, students, parents, admin, my parents, friends can see exactly what I say and do.
Simplemind Xpress: graphic organizer for the iPhone and home computer (syncs both). It has been great for keeping track of all the ideas for ONE, our campus news show.