Finally, someone who believes there should be balance! Most of the DX designers appear to either want to show off or don't know enough. I commend you on your decision mormegil. My advice would have to start here:
1. Work on your computer - but take note to what you do and where you go. This will aid in determing what you should be included for your DX.
2. Don't get side-tracked by things(that is tools) that would look cool - the key here is FUNCTIONAL. (Think in terms of what you would bring with you on a trip in a suitcase. You don't need a kitchen sink

) Don't be like that kid in the candy store, who wants it all!
3. Be as creative as you want! Yeah, you want it to be functional but don't sacrifice your work.
4. Do not add lists of programs the average person will not have on his/her computer. Remember, you have to be practical as well as functional. Don't have a list of 4 web browsers when you can just add one button that says internet, and let them tell it where to go.
Now having said all that, lets move on. One of the best things I think I have ever seen was a skin that was done for Winamp 3. It is called Invicta and was located on this website. If you want to get some good ideas on balance of functionality versus art, my advise would be to check it out.