FormatFactory

FormatFactory (MS Windows only) http://www.formatoz.com/index.html :
Media converter which allows conversion between a variety of different media formats.

Video Monkey

Video Monkey (Mac only) http://videomonkey.org :
Free video encoding software designed for the Mac OS X operating system

NameChanger

NameChanger (Mac OS X):  http://www.mrrsoftware.com/MRRSoftware/NameChanger.html
Free software designed to help batch renaming of file and folders quickly and with ease.  Among various renaming options, the software supports regular expressions, mismatched files types, and formatting changes.

Lupas Rename 2000

Lupas Rename 2000 (MS Windows): http://rename.lupasfreeware.org/lupasrename.php
Simple and powerful program to help rename file and folders.  In addition to being free, the software is just a simple ".exe" that does not require installation, so it is small and extremely portable.  Perhaps one of the programs that should be handy on a USB drive.

Flowing Fix: How do I get those data points off an image?

Every so often you need to read points (or entire curves) off a figure.  To expedite this process here are two freely available programs to digitize the points from an image.

Engauge (MS Windows, Linux [Mac OS X requires building])  http://digitizer.sourceforge.net/

Plot Digitizer (MS Windows, Linux, and Mac OS X ) http://plotdigitizer.sourceforge.net/

XLXTRFUN: MS EXCEL functions

ADD-IN for MS EXCEL  http://www.xlxtrfun.com/XlXtrFun/XlXtrFun.htm
following summary via xlxtrfun website:
"XlXtrFun.xll is a collection of functions which extends the capabilities of Microsoft Excel; developed primarily to facilitate, interpolation of 2-dimensional and 3-dimensional data, and simplify 2-variable curve fitting. XlXtrFun has been used for years by engineering and research and development personnel on every continent who need to interpolate, extrapolate, and curve fit data rapidly, reliably, and with a virtually non-existent learning curve.
If you work with real-life data and want to interpolate, extrapolate, or curve fit, then you will find these functions very useful."

PSPad

PSPad (Windows only) http://www.pspad.com/ :  
Text editor and source editor which is more powerful and useful than notepad and wordpad that are standard with Windows.  PsPad allows for row and column selection of text, macro creation, file comparisons, tabs for multiple documents, language syntax highlighting, regular expression find/replace capabilities,  among other advanced features.  You can either download portable version or install full version to integrate with Windows shell.

SyncToy

SyncToy (MS Windows only) http://www.microsoft.com/download/en/details.aspx?id=15155 :
Easy to use program to backup files