I've been running Apache HTTPD for seven years and it hasn't let me down yet. I am continually impressed at how configurable and stable it is. This goes without saying, as it is the de facto standard.
I first got a taste of 7-zip on windows, where it has been outfitted with explorer integration and a very functional GUI. It can handle some pretty intense operations (multi-gig archiving) where the built-in windows archiver craps out. I have since installed it on all of my Linux boxes and use it from the command line. It supports a great range of archive formats and is easy to use. I still use tar for making .tar.gz and .tar.bz2 archives out of habit, but 7zip has earned a permanent place on my unix toolchain.
One caveat: if you plan to use the native .7z format, make a tarball first if you want to preserve the permissions of your files.
VLC player is great because it is extremely versatile. While it lacks the polish you might find in another media player (and thankfully, also the bloat) you can get it to play *nearly* any type of multimedia including DVDs (VOB) and Flash Video (FLV), and it can even transcode between a huge variety of formats. It is also good at playing incomplete or damaged files, including partial downloads and damaged DVDs which can be handy.
It runs on a nice variety of platforms as well.
It's not my primary player, but it's a reliable workhorse and a must to keep around.
Beryl is a fun toy to play with, and it's great at impressing people who think that Linux still looks like Twm/Motif. It's the most futuristic and flashy window manager I've seen on any platform. Highly configureable via the Beryl-manager GUI. The "Desktop Cube" is a great metaphor and the fully rendered 3D cube is very, very slick. However, after the novelty wore off I went back to GNOME Metacity for the performace gain.
I use SciTE as my graphical text editor on my Linux box. It's nice because it doesn't have tons of dependenices like Kate or other editors tied down to a desktop suite. (I don't use KDE or GNOME so this is especially nice.)
I can't speak for Scintilla as a whole as I haven't tried it, but I would recommend SciTE for other desktop linux users, especially those who like to run lightweight systems.
Camino has a long history on Mac OS, and was on the scene before Firefox was a workable option. Even in its current state, I would argue that Camino is still the best Gecko browser on Mac OS. If you've used the Mac version of Firefox for any extended length of time, you'll realize that it's a memory behemoth and doesn't integrate well with the rest of the OS. I'm on a Mac mini with a limited amount of RAM, so speed and slimness are very important to me. (I was a windows user of Firefox so I used it for many months when I got my Mac, but have since switched to Camino.)
Supposedly Firefox 3.0 will bring some native cocoa features, but until then I'm sticking with Camino as my primary browser. The only real downside is less customizability through plugins (and themes if you're into that) although you can still tweak it internally with about:config and get some neat plugins at pimpmycamino.com.
I can't tell you how it is from an administration standpoint, but my university uses SquirrelMail for its webmail installation. They recently upgraded to 1.4.9a which is an improvement over whatever old copy they were running. A lot of the complaints that I had about the older version (getting logged out when working on a draft, etc.) have been fixed.
Not bad for an open-source solution, but your users will love you if you use a more polished system like Gmail via Google Apps.
I've been using NeoOffice for about a year, and OpenOffice.org for over two. I was worried about stability so I didn't try any of the Aqua series until it got out of alpha. Let me say that it's a vast improvement over the old NeoOffice builds, much as OOo 2.0 was to 1.0.
It still takes a while to start up, but once it's going it's pretty responsive. The aqua controls are also nice.
Coming from using MS Office and OpenOffice on Windows, I've never liked Office for Mac or AppleWorks. Thankfully NeoOffice has the full window and consistent toolbars that I'm used to in an office program.
It's too bad that there's been a bit of a falling out between this community and OpenOffice.org.
Very functional, if a bit crash-prone and lacking a few crucial features such as a search box. The tabbed browsing implementation is very nice, although tab focus should be more adjustable. Bookmarks are stored in categories instead of a folder hierarchy and are sorted alphabetically, which I find to be pretty useless. After a bit of poking around I figured out how to make a bookmark bar with drop-down folders like I'm used to. Overall a decent and very fast, lightweight gecko browser akin to Camino on Mac OS X. This is becoming my preference over the increasingly bulky Firefox (Iceweasel) on Linux. It even has some extensions.
I like w3m, but I find lynx a bit more intuitive when it comes to keyboard controls. I guess it has better standards support, but I like lynx because you can get it to run the same under virtually any environment.
I'll have to try w3m out with mouse support, as I'm sure this is part of the advantage.