Bitmask is an open source application to provide easy and secure encrypted communication. You can choose among several different service providers or start your own. Currently, Bitmask supports encrypted internet (VPN) with encrypted email coming soon
Asynchronous Filesystem Replication: SFS is designed for GNU/Linux systems and is based on FUSE
Linux tool to show progress for cp, rm, dd, ...
Alternative firmware for the DNS-323
sysql - use sql queries against output of linux commands
Intrusions can take place from both authorized (insiders) and unauthorized (outsiders) users. My personal experience shows that unhappy user can damage the system, especially when they have a shell access. Some users are little smart and removes history file (such as ~/.bash_history) but you can monitor all user executed commands.