Here's some helpful ebook cover resources I found recently.
Ebook Cover Design Step by Step Tutorial using Paint.net (very cool and shows cover for Blood Moon by Tori Minard)
How to Create Banner with Paint.net (killer tutorial that shows you how to work with layers and works for ebook covers too)
How to Create 3D Ebook Cover for Free with Paint.net (great for those who want 3D image to go with their 2D image)
eCover Software Pro ($27 but you can quickly import 2D ebook image into 28 3D covers that can be saved at any size which is great for those bundling ebooks with dvd, cd, coaching, mp3, iphone apps, etc.) I got this software Friday and it is so easy to use.