I have an image on my blog that has a border around it. I like the border effect but I want to change the color of the border. Does any one know how I might do this?

If this image has a link around it, you'll need to remove the border and add a style definition to it:



etc.

Is there a plugin that can do this automatically when you create an entry with an image in it when using the "Upload File" feature?

You might be able to create a plugin that would do it, but you would probably be better off updating your stylesheet for the img tag to change the border to be whatever color you would like. Then you only need the img tag. If you only want it in certain places, then place your entry body in a div and only style the img when it's inside that div.