Paint.NET

Microsoft has a bad habit of bundling, then scrapping image tools for Office, which always leaves me at a loss for a decent image tool. I inevitably end up using 3-4 different tools to do anything: 1 for scanning, 1 for editing, 1 for cropping and resizing (most do a lousy job of it), another for saving to the format I want.

Enter Paint.NET. It's got all the features I need (plus layers and some others), and it's FREE.