One of the ways that I organise computer time for students is by utilising the website Delicious. It's a simple concept - take the idea of bookmarks that you keep on your desktop and broaden it out so that your bookmarks are available anywhere you have internet access. Your bookmarks are accessible via a url - like this -> http://delicious.com/hey.milly.
I've been using delicious as a way of organising my own links and sharing links through conferences for a few years. Last year I started using this in the class also and the kids quickly got a hang of it. This year with my Year 4 class I am also using the same idea - they have also quickly figured out how to access and use their delicious page.
The first thing I do is set up a class delicious account e.g. http://delicious.com/twelve2010 that the students access to get their bookmarks. I start with one curriculum area and teach the basics of how to access it and find the links you want.
The great thing about Delicious is that when you add a link into your account you can tag the link with a keyword. For example if I took the link Questionaut I could tag it as several different areas like thinking, problem solving, maths and more depending on where you wanted to keep it.
As you create your own tags this allows you to easily tag links for specific groups, curriculum areas or teaching points that you are working on with the students.
When students come to work on the computer - their taskboard will pinpoint the tag that they will look for when they get to Delicious e.g. Addition This also gives the students some ownership in choosing tasks that they feel confident with and need to work on. There are also a range of websites that the students can use to develop that teaching point or need.
Currently I am the only one adding links to the delicious, but would like to move forward to the kids finding great sites and being able to share them or add them to the class Delicious page.