XnShell is a handy Explorer shell extension which makes it easier to view, process and generally work with images.
The program allows you to preview any picture, in just about any format, directly from its right-click menu. No need to turn on Icon View, enable the preview pane or open the full image (which may not work, anyway, if it's not supported by your default viewer): just right-click, select XnShell, and you'll see a thumbnail in the context menu.
You're able to convert your selected files directly to GIF, BMP, JPG, PNG, PCX, TIF and TGA from the context menu.
A separate "Convert…" option opens a dialog with more formats, resize options, and the ability to set your output folder.
There are simple options to rotate the image by fixed amounts (or according to the EXIF tag), flip it, or edit its IPTC tags.
An Upload tool sends the picture to ImageShack and opens it in a browser window, ready for immediate sharing (no registration required).
Other options can send your selected image to the clipboard, or set it as your wallpaper.
This is all configurable via a detailed Options dialog. In particular, you’re able to customize the program menu to remove features you’ll never use.
XnShell doesn't do anything too surprising, but the value here is all in the shell integration. If you occasionally work with images from Explorer then the program should help make your life a little easier.