Bali's Calc is a nice scientific calculator for DOS. It does base 10 and natural logarithms, extracts nth roots, raises to nth power, does trigonometric functions and inverses, factorials, and more. It likes a mouse, but you can also arrow around the keypad, or just type in numbers and basic functions (+, -, /, *).

Unfortunately, I've found that some 8088s won't run this calculator. If yours won't, you can still use Calc75, a simple four-function DOS calculator. It's extremely small, doesn't use a mouse, can be moved around the screen, and is absolutely free.

Popup Slate is a very small, handy notepad that you can pop up anywhere -- at the DOS prompt, or within any program. It's a TSR that's loaded at bootup, but takes only a tiny amount of RAM. It isn't fancy, but if you need to jot things down quickly, it makes a handy replacement for pencil and paper; plus, it saves what you've written even when your computer is off.

If Popup Slate won't run on your computer, you can try Notepad, which runs just fine for me even on an 8088. In fact, Notepad has some cool extra features, like ability to paste text outside of Notepad, and to use a mouse.

Mac-ette is a DOS program for copying files to and from Macintosh formatted 1.4MB floppies. And as if that weren't cool enough, Mac-ette will even Mac-format a floppy, right from your DOS box! If you (or a friend) have a Macintosh that takes standard floppies (Mac-ette doesn't work on 400K or 800K floppies), this is a really useful tool, and helps lend DOS the cross-platform compatibility that Macs have had for years.

Long before there was a Windows File Manager, there were graphical tree-style file utilities for DOS. XTree was certainly one of the first of these, and offers some distinct advantages over command-line file management (such as quickly tagging just those files you want to copy or delete -- even if they don't all begin with the same letter, or end with the same extension). Xtree has been in development for years, and it's still available.

TreeTop is another program in the same spirit, offering somewhat different capabilities than Xtree.

Checksys is a little command-line utility that gives you a readout of your system specs: processor speed, coprocessor, video hardware, mouse, packet driver, expanded/extended memory, and so on. Kinda like MSD on the cheap.

F-Prot is an anti-virus program for DOS, which is updated frequently by the author to make sure you've got the latest virus information. (Note: F-Prot isn't small -- it takes about 1.5 Meg on your hard disk -- and on a 286 it can take a long time to scan, so run it when you're off watching cartoons or something.) F-Prot is by Fridrik Skulason, and is free for non-commerical use.

Crack Editor is, despite its fearsome name, really just a handy little hex editor for DOS. It can open programs, translate from decimal to hex notation, has a calculator, a screen saver, and more; yet it runs on a 286, requiring only 200K of RAM and EGA graphics. If you don't know what a hex editor is, you probably don't need this (and if you use it on a program without knowing what you're doing, you can make the program unusable, so at least make a copy before you go joyriding). But if you want to hack out certain noxious 'features' from some abandonware, Crack Editor lets you do it on the cheap. Crack Editor is by Toni Makela, and it's postcard-ware (the author asks that you send a postcard to his address, listed in the docs).