I am not a designer. But using some sample code that one of our engineers (Glenn) provided I have a created two simple themes that can be used with the Spark skins for changing the colors of your application. One of the cool new features in Flash Builder 4 is our Theme Chooser, so these are designed to work with that. Simply download this zip and expand it. Make sure you keep the subfolders for now, then in Flash Builder you can import the SWCs either from the project properties or in the Appearance panel when you choose the theme. Right now FB will say that it's copying the whole folder, we're going to look to change that after Beta 2. Also you'll need to remove the hyphen from the name to make it legal (I chose those names for the SWC to enable some style features, but those won't be necessary after Beta 2 either).
The source is included in the form of fxpl projects. You can import those into Flash Builder and edit away. Make sure that if you add new files you go into your project settings and re-select all the files to be included. We have a bug currently where if you just do the checkbox that includes everything the skins likely won't work.
The goal here is to show how easily you can change just a few style properties and have a very different color theme running in your app. By the time we ship the custom skins that I included shouldn't be necessary and we'll hopefully need even fewer entries.
