Prey is a silent tracking program that you can install on your computer. If your computer goes missing, you can log in to their website to help track it down when it reconnects to the Internet.
TeamViewer is a great program for remote assistance and screen sharing. Installation is required on the server end, and the client just needs to download a small self-removing file to complete the remote connection.
Connectify is a simple program that lets you turn your laptop's WiFi antenna into a receiver for other devices (ad-hoc network). Your laptop must be plugged into a network via ethernet to provide Internet access to the other devices.
Google Docs is one of the most popular document storage and sharing websites. Any doument can be uploaded for storage. Text documents, spreadsheets, presentations, and drawings can be edited online. Documents can be shared with other users and multiple editors can access and make changes to a document at one time.
Dropbox is a cloud storage program. It creates a folder on your computer that automatically syncs with an online service, giving you access to your files on any other computer which you install Dropbox on. It also has a version for iPhone and Android devices.