Deleted

Gimp.

GIMP or IrvanView.

GIMP.
alternatively, PS CS2 is freeware for quite a while now. (edit: oh, don't want photoshop, huh?)

if you just want to resize/convert an image, then the good ol' MS Paint can do that for you too.

I use IrfanView for viewing and minor editing, GIMP for more advanced touching up and editing, and a little Paint.NET on the side.

http://www.totalcmd.net/plugring/imagine.html

I love FastStone, but also use XnViewMP for organization and mspaint.exe or Paint.NET for editing

XNview is also good

Google Picasa

XNview

Viewing -- Irfanviw
Editing -- Paint.Net

+1 for Irfanview -- I'll usually use Photoshop for actual editing things, but Irfanview starts up so fast, it's invaluable for quick edits (crops, and other minor things)

For viewing lots of images though, ACDSee is still king (I have a photographer friend who still uses version 2.something for its speed), but I use those feature so rarely I never even end up installing it. Irfanview's mass image browser is fairly quick and IIRC, can browse through subfolders with the right settings.

Been using XnView since it got out and it's cool.
Never wanted anything else.
Tons of features, easy to use, and it's really fast, unlike InfraView.
But it depends on what you want.
XnView has resize, convert, filters, crop and other features but nothing Photoshop like.
For that Paint.NET is the best.