underrated apps?

[Somenoob]

Aptitude comes to mind, not it's common usage but it's menu, it is often overlooked. It enables you to install, browse quickly and easily.

[blithen]

Cmus: Command line music play very easy to use.
Probably Glipper too. It's a clipboard manager for GNOME.

[Mud.Knee.Havoc]

I agree with cmus... it's a great program, and the only cli music player that I've tried that'll display UTF8 correctly.

So here's my quick list of underrated apps:
- openbox, pypanel and feh (to give you a nice looking, quick desktop)
- rtorrent
- screen
- cmus
- htop
- tkremind
- quod libet
- conky

Screen is a fantastic utility that will let you use a single terminal window to run a number of different windows (even split a terminal window in two!). I usually use screen to display htop (the best program to see which processes are using the most CPU/memory) on the top half and rtorrent (best torrent client - I can have 6 - 10 torrents going at once and it's only eating up 3% of my resources!!!!) on the bottom.

Tkremind is a very powerful calendar that will use very few resources as well.

Quod Libet is my favorite music manager (like juk, amarok, etc), since it's got some very good plugins and can handle all encodings. It's better than those programs mentioned in terms of CPU load, but cmus is far lighter. :D

Conky displays whatever statistics you'd like on your background, sort of like a heads-up-display.

[FuturePilot]

Htop is great! It's like top only 10x better. :D
I love Conky too.

[toupeiro]

Streamtuner

Every time I host a party, people are like -- wow thats a great set of music.

[andrek]

MPD - Music Player Daemon
Sonata - GTK MPD client

[qazwsx]

Konqueror as webrowser.

[macogw]

Oh I agree on screen, but I think it's most useful on a server. You don't have to background tasks or open up a second tunnel to the box. You can also keep the session running when you disconnect then reconnect to it from another box and see, for instance, your irssi or whatever you have running instead of killing the program when you disconnect from ssh.

[crimesaucer]

Wicd: http://wicd.sourceforge.net/