A little list of some nifty packages for Debian:
Oddly enough this isn’t installed by default. Well known for most Linux users, but it enables regular users to perform commands as root without actually logging in as root.
Protects you from shutting down wrong server when using ssh to a server. What it does is ask you which server you want to shutdown when you run the command shutdown. If you type in wrong hostname it won’t run the command. Handy if you have a bunch of ssh sessions open and you type shutdown in the wrong session.
Generates random passwords. Configurable what kind of passwords you want, for example high complexity and so on.
Can be used to check the performance of harddrives
Widely used imap/pop server
Widely used smtp server. Often used in conjunction with dovecot
A package for webmail. Requires of course a webserver, for example apache
A genius monitoring software, can monitor just about anything using smtp, ping, telnet and so on. For more information, check zenoss.org
A network traffic monitor. It gathers statistics provided by the kernel and can present them to user either by text output or graphs.
Can lock on or more sessions on the console allowing others to use the console.
Log colorizer. Useful when investigating large logs
Rather flexible package for automating e.g. download of package updates. Can be configured to check updates every night and send an email containing the list of updates for example
Can be used to open up multiple terminal windows, which can be detached and resumed later
Examines a range of logs and if and IP makes too many bad logins, fail2ban creates firewall rules to reject traffic from that IP
A web based administrative tool. Can be used to administer apache, file sharing, dns and so on
File and print services for any client using smb/cifs, e.g. windows
Opensource vmware tools. Follow the guide on this site: http://www.surlyjake.com/2011/02/install-open-vm-tools-on-debian-6-squeeze/
I will update this post with more as I remember them :P