Owl Intranet Knowledgebase Useful for businesses of many sizes, Owl is a multi-user document repository, as well as a document management system. It allows you to easily publish documents on the Web for collaborative sharing and peer review. One major advantage: its highly scalable, meaning it grows as your needs grow. It's Web-based, so its OS-independent.
eGroupWare: Enterprise Collaboration You didnt think file sharing was just for people, ahem, building their music collection, did you? Equipped with a Web interface, eGroupware enables serious inter-office communication between far-flung workers. It helps the whole staff keep up with their contacts, appointments, and to-dos. OS: Windows, Linux, Mac.
FileZilla The appropriately-named FileZilla is a veritable Godzilla of FTP and SFTP clients. Its fast, and has all the essential tools built in: configurable speed limits, filename filters, large file capability (that ones important). Plus it has a real cool name. You can say to friends, Hey, lets use FileZilla" (then let out an animal roar). That will definitely impress them. OS client: Windows, Mac, Linux. OS server: Windows only.