I often struggle to make Swing applications to look good, or even make them vaguely look like I intended. The different JFrame layout options and all the coordinates of where to place what and how long is that makes the creation of Swing interfaces difficult.
Since I don't like using different development environments and got very used to Eclipse for anything I need to do, I was looking for a good graphical GUI builder that works as a plugin for Eclipse. I came across this really nice one: Jigloo from CloudGarden
It's pretty easy to install into Eclipse, via update site: http://cloudgarden1.com/update-site
and then creates GUIs by drag and drop in a way that I thought wouldn't have been possible. The commercial use of this product is prohibited without license, but this shouldn't stop any hobby programmer, much like myself, from using this great product.
Here is a screenshot I leeched off their site (I might attach one or two myself):