In a small “introduction to Linux” class I was helping out with recently, I did a short demo of how Wireshark can show you what happens when you load a webpage (and, also, what gets broadcast on wireless networks 🙂 ). (No, it’s not a Linux-only program, but it is a mature, easy-to-use open-source application that runs on Linux and is in most software repositories.) I was asked for examples of other interesting (presumably, to broad swaths of geeks) applications, so here are a few:

I Use It And Like It

Wireshark

The continuation of Ethereal. Analyzes traffic going through your network interfaces.

Audacity

Easy-to-use audio-editing tool.

Totem (with Xine backend)

Totem is the GNOME movie player. It integrates nicely with the GNOME environment, but at least as of a year or so ago, you were better off using the version compiled using the Xine libraries because of broader media support. If you use Fedora, you may wish to add Livna to your repositories, as it includes totem-xine. It would also be worth checking out Stanton Finley’s Fedora Core 5 Release Notes for information on how to extend the number of codecs supported.

OpenOffice

Cross-platform open-source office productivity suite.

Firefox

Open-source, highly-extensible web browser. (I posted recently about a couple of my favorite extensions.)

Thunderbird

Open-source email client.

I Hear Good Things About It

Azureus

A popular and full-featured BitTorrent client. It’s Java-based, so it runs everywhere (*giggle*).

Eclipse

Eclipse seems to be the graphical open-source IDE for doing development in Java and C/C++ right now. It appears that there are also plugins for PHP, Python, and others, but I don’t know how mature they are.

It Sure Looks Cool

Ekiga

Open-source SIP/H.323 a audio- and video-conferencing program. Interoperates with programs like Microsoft’s Messenger and NetMeeting and Apple’s iChat.

Feel free to jump in with your thoughts and favorite applications.