Notetaking is an inevitable part of any students life. It might be taking notes from lectures or books, planning essay structures, to-do lists and much more. Arguably the most mobile notetaking form is pen and paper. While this medium has many affordances such as micro-mobility, read-write-rewrite and personalisation, there are a number of notable limitations. For example, written notes aren't easy to index, organising them can be time consuming, sharing notes for collaboration is limited, transportation of large amounts can be troublesome. More students are using electronic devices to supplement 'traditional' notetaking and there is a growing number of specialised notetaking software and web services. Many of these solutions also appear to dovetail nicely against new study styles and ways of working.
One such solution which I've been recently test driving is Evernote. Evernote is designed to allow you capture notes (including typed text, handwritten notes, web clippings, photographs, sound recordings and much more) on a wide variety of devices and platforms, allowing you to synchronise with their online web service. The basic signup is free which gives you a 40MB monthly allowance, which is more than enough for me. Your notes remain private and there isn't currently a system to share them with other users, you can however email them to friends or theoretically directly to other web services like Flickr and Google Docs (I was unable to directly email from Evernote to Google Docs. I think Evernote is struggling with the upload email address provided by Google).
It is possible to organise notes by tagging them and putting them in different notebooks. All of this information is accessible and searchable by any device with a browser and an Internet connection. Even text in images is indexed where possible making it searchable.
There are of course other note taking tools and other web services you could use. For example you could use a basic text editor and use your email inbox as a repository. There are also standalone packages like Microsoft's OneNote which you can synchronise with a Window's Mobile device. What I like about Evernote is they way they have tried to cater for multiple platforms and devices integrating it with an online service which gives me access to my notes anytime, anywhere.