Tiny Windows programs you can't live without:

[minipol]

zonealarm, keeps hackers out of the system (hopefully)

[atari_eric]

Originally posted by Suicide Junkie:
Why would you need to reduce your resolution to play SE4?
Unless you've got some incredible rez like 1600x1200 or something as your usual it'll look fine.

Yeah, it'll work fine, it's just easier on the eyes than having a small screen in the center. I usually run 1280x1024, but I have been known to go to 16x12 for programming (to see ALL the code at once!)

[Suicide Junkie]

Trillian hasn't been mentioned:
An excellent 3meg program that does IRC, MSN, ICQ, AIM, and Yahoo all in one.

[Lemmy]

I only 2 programs which haven't been mentioned yet.
The first a little calculator named KolQl8or, made by a friend of mine, very handy if you need to calculate something, works way better then the windows calculator imo, mostly because the equations can be entered and modified in one texfield.
The second is CuteFTP.

[Ruatha]

Powerarchiver.
Older Versions are freeware and unpacks, ACE,ZIP,RAR and plenty more.
And multi-pack/unpack in a better way than Winzip.

[dogscoff]

media jukebox - kicks the poo out of winamp, sonique, WMP etc becasue it handles all sound and video file formats. Very sturdy and well-supported, loads of cool features even in the freeware Version, and some excellent "smartlisting" features as well.

Oh, and it's not exactly indispensible, but I often use a nifty bit of freeware called ckrename, which is handy for bulk renaming of files (good for shipsets).

[Elwood Bluze]

Baron Munchhausen, I found Quickzip:

http://www.quickzip.org/