Not sure about FreeStone that Dan is referring to but I remember the very good program I heard about it from Christine called "FastStone". Here is a link to the site and download
LINK. First download, Viewer is what I am talking about. Rest are useful downloads too.
Matt; Picasa is the best program out there you must have, especially if you are to start post processing as beginner or just need to have a good organization of your images on your computer. It also gives ease of sending several images at right size etc by email. In short it offers too much for nothing that I am surprise why they give it free. Thanks to Google and hope your stock price go even higher (Only regret, not to buy them when first came out at $70 a share). Of course my other complain is that it is not available for Mac (To the best of my knowledge) so poor mac users need to suffer as usual. Well back to Picasa, that was my gate way to photoshop that is inseparable part of my photography today, but still I enjoy using Picasa for fun of it.
Here is download
LINK to Picasa if anyone needs.