Desktop Enhancements:

Autohotkey - http://www.autohotkey.com/
AutoSmall - http://www5e.biglobe.ne.jp/~wingdog/soft1.html
AveDesk - http://www.aqua-soft.org/board/showthread.php?t=17372
Clocktrayskins - http://www.drive-software.com/windowsclock.html
CursorXP - http://www.stardock.com/products/cursorxp/download.html
Desktop Sidebar - http://www.desktopsidebar.com/
Filehand - http://www.filehand.com/
Glass2k - http://www.chime.tv/products/glass2k.shtml
Kapsules - http://kapsules.shellscape.org/
Launchy - http://www.launchy.net/#intro
Locate32 - http://locate32.webhop.org/
Lost Goggles - http://www.lostgoggles.com/
Menu Inventor - http://micron.ic.cz/menuinventor
MouseIMP - http://www.mouseimp.com/
Panorama - http://www.ivory.org/panorama.html
Qliner Hotkeys - http://www.qliner.com/hotkeys/default.htm
Rainlendar - http://www.rainlendar.net/cms/index.php
RKLauncher - http://home.cogeco.ca/~rklauncher/
RunFast - http://www.idiogensoftware.com/runfast/index.htm
Samurize - http://www.samurize.com/
SlickRun - http://www.bayden.com/SlickRun/
Snippy - http://www.bhelpuri.net/Snippy/
Taskix - http://taskix.robustit.com/
TaskSwitchXP Pro - http://www.ntwind.com/taskswitchxp/
Trip - http://trip.glenmurphy.com/
Weather Watcher - http://www.singerscreations.com/
WinRoll - http://www.palma.com.au/winroll/
Yahoo! Widget Engine (Formerly Konfabulator) - http://widgets.yahoo.com/

Download managers:

Flashget - http://www.amazesoft.com/index_en.htm
Free Download Manager - http://www.freedownloadmanager.org/
Fresh Download - http://www.freshdevices.com/freshdown.html
Gigaget - http://www.gigaget.com/
LeechGet - http://www.leechget.net/en/
Retriever - http://www.halogenware.com/software/retriever.html
Star Downloader - http://www.stardownloader.com/downloads.php
Sun Download Manager - http://www.sun.com/download/sdm/index.xml
wackget - http://millweed.com/projects/wackget/
wget - http://xoomer.virgilio.it/hherold/
WellGet - http://www.wellget.com/
WinBITS - http://www.darvin.de/english/
wxDownload Fast - http://dfast.sourceforge.net/index.html

Educational Utilities:
Kicad - http://www.lis.inpg.fr/realise_au_lis/kicad/
Molecular Workbench - http://mw.concord.org/modeler/
Periodic Table - http://paulalanfreshney.com/education/pt/
SciCraft - http://www.scicraft.org/
Scilab - http://www.scilab.org/
XCCalc - http://www.geocities.com/hjsmithh/Calc/XCCalc.html