If you need to reduce the size of an existing image in your posts or pages only a very small amount, you can easily do it through the text editor, like this:

UPDATE:  Mark pointed out that the proportional dragging feature that I show here does not work in Internet Explorer 8 (and earlier versions as well I believe).  When you try to drag the corner, the image does not maintain its relative dimensions – I even tried holding down the SHIFT key, but that didn’t help either. We know it works in Firefox (Mac or Windows) and may in other browsers – any comments on this issue would be appreciated.