I've bolded some of the most useful free ones that you may want to check out.

7-Zip 9.07 beta
Adobe AIR
Adobe Dreamweaver CS4
Adobe Flash Player 10 ActiveX
Adobe Flash Player 10 Plugin
Adobe Illustrator CS4
Adobe Photoshop CS4
Adobe Reader 9.2
Any Video Converter 2.7.9
Apple Keyboard Support
Apple Software Update
ArGoSoft Mail Server .NET Freeware
ATI Catalyst Control Center
ATI Display Driver
Audacity 1.3.9
avast! Antivirus - best free anti-virus software, uses low resources
BurnAware Free 2.4.1 - simple, easy to use CD/DVD burning software
Canon iP90
CCleaner - one of the best free apps, cleans your computer of junk files
CDBurnerXP
ClipX
Defraggler
DivX Web Player
Everything 1.2.1.371 - finds anything on your computer
File Extension Changer 3.3
File Shredder 2.0
FileHippo.com Update Checker - scans your computer for out-of-date software
FileZilla Client 3.3.0-beta1
foobar2000 v0.9.6.9 - best music player, very low resources
Fraps
Google Chrome
Google Earth
Google SketchUp 7.1
GTK+ Runtime 2.14.7 rev a
High Definition Audio Driver Package - KB888111
Input Remapper
Intype 0.3.1.734
IrfanView - best pure image viewer w/ a lot of options
Java(TM) 6 Update 17
K-Lite Codec Pack 5.4.0 (Full) - use this w/ Media Player Classic for the best video player
LAME v3.98.2 for Audacity
Left 4 Dead 2 Demo
Macintosh Drivers for Windows XP
Magic Video Converter Trial Version (English) 8.0.2.18
Malwarebytes' Anti-Malware - best spyware cleaner
Microsoft .NET Framework 1.1
Microsoft .NET Framework 2.0 Service Pack 2
Microsoft .NET Framework 3.0 Service Pack 2
Microsoft .NET Framework 3.5 SP1
Microsoft Compression Client Pack 1.0 for Windows XP
Microsoft Kernel-Mode Driver Framework Feature Pack 1.1
Microsoft Office Enterprise 2007
Microsoft Silverlight
Microsoft User-Mode Driver Framework Feature Pack 1.0
Microsoft Visual C++ 2005 ATL Update kb973923 - x86 8.0.50727.4053
Microsoft Visual C++ 2005 Redistributable
Microsoft Visual C++ 2008 ATL Update kb973924 - x86 9.0.30729.4148
Microsoft Visual C++ 2008 Redistributable - x86 9.0.30729.17
Microsoft XNA Framework Redistributable 3.0
Moffsoft Calculator 2
Mozilla Firefox (3.5.5) - best web browser
Mozilla Firefox (3.6b1)
Mozilla Thunderbird (2.0.0.23)
Mozilla Thunderbird (3.0b4)
MSXML 4.0 SP2 (KB954430)
MSXML 4.0 SP2 Parser and SDK
MSXML 6.0 Parser
Notepad++
Opera 10.01
Opera 10.10
Orbit Downloader
Paint.NET v3.5 - best replacement for Microsoft Paint
Password Safe - stores all your logins and passwords for various sites
Pidgin - great all-in-one instant messenger app
Pinnacle TVCenter Pro
PrimoPDF -- by Nitro PDF Software
QuickTime Alternative 3.0.1
Real Alternative 2.0.1
Realtek High Definition Audio Driver
Recuva
Revo Uninstaller 1.83
Safari
SigmaTel Audio
Skype™ 4.1
Spelling Dictionaries Support For Adobe Reader 9
Steam
SUPER © Version 2009.bld.36 (June 10, 2009)
Taskbar Shuffle version 2.5
Tweak UI
Unlocker 1.8.8
Update for Windows XP (KB943729)
Vegas Pro 9.0
VLC media player 1.0.3 - another fantastic media player
WampServer 2.0
WinDirStat 1.1.2 - shows every file in your system and how much space each takes up
Windows Internet Explorer 8
Windows Live Essentials
Windows Live Sign-in Assistant
Windows Live Upload Tool
Windows Media Format 11 runtime
Windows Media Player 11
Windows XP Service Pack 3
WinRAR archiver
XYplorer 8.60
Youtube Downloader HD v. 1.6 - great way to download youtube videos
µTorrent

Here's my list, I'll bold the ones I think are must haves

uTorrent
7-Zip
Adobe Acrobat Reader 9.0
Adobe After Effects CS4
Adobe Bridge CS4
Adobe Encore CS4
Adobe Media Encoder CS4
Adobe Premiere Pro CS4
Adobe Soundbooth CS4
Adobe Flash CS4 Professional
Adobe Flash Player 10 Active X
Adobe Flash Player 10 Plugin
Adobe Photoshop CS4
Alcohol 120% - Best virtual drive emulation software by far
Apple Application Support
Apple Mobile Device Support
Apple Software Update
AutoCAD 2010
Autodesk Design Review 2010
AVG 9.0 Professional
Axialis Icon Workshop - Excellent Icon creating and Editing software
BitPim - good program for moving things to and from your cell phone via USB
CCleaner - One of my most frequently used programs. Cleans literally everything!
DivX Codec
DivX Converter
DivX Player
DivX Plus DirectShow Filters
DivX Web Player
EA Download Manager
FLOCK - crazy sheep herding game by CAPCOM
Internet Explorer
iTunes
Magix Music Maker 15 Premium - Excellent music making software
Magix Samplitude Music Studio 15 - Excellent music producing software
Microsoft Office Home and Student
Mozilla Firefox - Hands Down best web browser period.
Quicktime
RocketDock - Mac-like Dock for Launching Programs
Sony Acid Pro 7 - pretty good music editing software
UltraISO Premium - not the best, but an okay drive emulation program
VMware Workstation - Best program for beta testing or testing in general a new OS
WinRAR

I always see CCleaner and Firefox as universally recommended apps. And for good reason too.

wow this topic makes me think i'm pretty ignorant when it comes to software. i'll definitely have to get some of these.

how often do you actually use Microsoft paint? Just wondering. :)

Well I have Photoshop CS4, so in my case, Never. But it is rather cool looking in Windows 7. They gave it a ribbon like Microsft Office Programs have. WordPad was also given a ribbon.

There are some things I do that are kind of overkill for Photoshop. Like if I were to take screenshots of something or just do some cropping, I would just paste them into Paint.NET and save them, since it opens much faster than Photoshop.