e3 text editor
The e3 console text editor takes minimalism to the max - the binary is a minuscule 13KB in size! So why use this instead of [insert the name of your favorite editor here]? If you're anything like me, you'll find a lot of your editing tasks are very short -- little more than tweaks. e3 starts instantly and has all the basic features you could want, including find/replace, block cut/copy/paste, and undo. For complex tasks I use a more feature-packed program, but for a quick change to /etc/fstab or something similar, this little editor wins every time.
e3 also does its best to be ubiquitous. It works on a whole host of operating systems, and perhaps best of all, it supports keyboard mappings that emulate WordStar, Pico, emacs, vi, and Nedit. You can hardly fail to feel at home with it.
Xfce window manager
GUIs tend to fall into two camps: the huge (KDE, GNOME) and the tiny (Fluxbox, FVWM). Xfce stands in the middle ground, offering more speed than the former, and more features than the latter. The interface is slick, clean, and highly responsive, even on slower machines. While it's less configurable than the big boys, there's enough here to keep most people happy, and the Xfce Goodies project offers a number of useful plug-ins for the main panel.
Personally, I don't get on with Xfce's native file manager, but Xfce is GNOME and KDE compliant, so a quick search on SourceForge or freshmeat provides alternatives and additions galore. The imminent 4.2 release looks set to improve things across the board and will hopefully give Xfce the profile it deserves.
GQview graphics viewer
I was always frustrated with the standard KDE and GNOME graphics viewers; they never quite behaved the way I wanted them to. Then I found GQview, which has an eminently practical layout and a sensible feature set ideal for viewing digital photos.
Opera Web browser
This one's going to get me into trouble. No, it's not open source, and yes, it is ad-ware, but no matter how much I like Firefox and Konqueror, I always find myself returning to Opera. It's thoughtfully designed, constantly innovating, and standards-compliant -- just the way commercial software should be. Opera is also jam-packed with goodies for the power surfer. Along with tabbed browsing, cookie management, and a pop-up blocker, there's the ability to re-open windows you've accidentally closed, a robust e-mail client that behaves like a database, and lots of other stuff. I've become so enamored by mouse gestures that I find myself frustrated when they don't work in other programs.
Many complain about Opera's advert banner, but I find it almost unnoticeable, especially since I choose the Google ads, which take up no more space than a toolbar. And although it's closed source, Opera is still pretty secure, and the few vulnerabilities that do crop up tend to be fixed quickly. Unless you're dead-set against commercial software, I'd recommend a test drive.
gFTP FTP client
I find using command-line FTP for more than the most trivial tasks hugely painful. gFTP is one of the most mature and full-featured graphical FTP clients I've found, but it maintains an elegantly simple interface. You connect by entering Host, Port, User Name and Password, then transfer files between the Local and Remote file panes by dragging and dropping. It couldn't be much easier.
gFTP has a simple browser-style bookmark system, a tree view of file transfers (good for checking that all those nested subdirectories are being downloaded) and supports basic file operations on local and remote systems. I FTPed the whole of SUSE 9.0 with this program (8GB spread across many thousands of files) and it behaved impeccably.
There are a number of reasons for using a small program over a larger one. Small apps are often faster, simpler, and -- by virtue of code complexity, or rather lack of it -- more stable. I hope I've encouraged you to try at least one program you haven't used before. Sometimes small really is beautiful!