PerlShare is a DropBox drop-in to create your own private file sharing "cloud". It consists of two parts; a client and a server. The server part lets you configure a Linux machine to accept PerlShare clients. PerlShare behaves a lot like DropBox. On collisions, for example, it creates conflicted copies. The workhorse for synchronization is Unison, a very reliable piece of software from Pascal Bach.
GroupOffice is a groupware suite that takes your office online, implementing online collaboration and CRM. It allows you to share projects, calendars, files and email online with co-workers and clients. It is easy to use and fully customizable. It also features synchronization with PDAs and Outlook.
PeerProject is a versatile peer-to-peer filesharing client and file manager. It's intuitive and aesthetic while supporting many networks and features, including BitTorrent, G2, Gnutella, eDonkey, DC++, IRC, HTTP/FTP, and more. It's a mainstream fork of Shareaza p2p, for Windows and WINE.
gPodder is a Podcast receiver/catcher written in Python and pyGTK. It manages podcast feeds for you, and automatically downloads all podcasts from as many feeds as you like. If you are interested in Podcast feeds, simply put the feed URLs into gPodder and it will download all episodes for you automatically. If there is a new episode, it will get it for you. It supports download resume, if the server supports it.
YaCy is a search engine that anyone can use to index the Internet (WWW and FTP) or to create a search portal for others (Internet or intranet). The scale of YaCy is limited only by the number of users. and can index billions of web pages. In P2P mode it is fully decentralized. All users of the search engine network are equal and it is not possible for anyone to censor the content of the distributed index.
CryptoHeaven offers secure email and online file sharing/storage. Its main features are secure and highly encrypted services such as group collaboration, file sharing, email, online storage, and instant messaging. It integrates multi-user based security into email, instant messaging, and file storage and sharing in one unique package. It provides real time communication for text and data transfers in a multi-user secure environment. The security and usability of CryptoHeaven is well-balanced; even the no-so-technically oriented computer users can enjoy this crypto product with very high level of encryption.
Coquelicot is a “one-click” file sharing Web application with a focus on protecting users’ privacy. Its basic principle is that users can upload a file to the server, and in return they get a unique URL which can be shared with others in order to download the file. Coquelicot aims to protect, to some extent, users and system administrators from disclosure of the files exchanged from passive and not-so-active attackers.