One thing I'm using more and more is the "Forms" feature in Google docs. (You will need a gmail account.) This feature allows students to fill in a record (ie. a line, or record) on your spreadsheet using a webform. Students can't see the completed spreadsheet, but each time s/he fills the form in, the data gets added to your Google doc.
How can I use it?
You could use this to collect survey information, write a quiz, as a pre-test to find out what your students know, to collect "quickie" book reviews, as sign-in sheets, for journal entries, collecting anonymous tips, etc, etc.
There are some great ways to play with the data once you get it, (graphs, charts, etc) and you can export the data into an excel doc for even more options.
How does it work?
Go to google docs, create a spreadsheet, and then build a form that will "sit on top of" the spreadsheet. Once you have finished composing your form, you can get a link to email or put on a website, or even embed the form on a page you have created. If it sounds complicated, it's not. Just spend some time with the videos listed below and you'll be a forms "expert" in no time.
Here are a few video tutorials:
Getting Started with Google Docs Forms
Going Paperless with Google Forms
Using Google Forms to Create a online Quiz
Self-grading google forms