Hi, I just wanted to show you one of my Arduino projects, its my quite simple, but instrumentalwise playable controller; 189014ctl.
Check out some pictures at : http://marcus.wrango.com/index.php?option=com_content&task=view&id=51&Itemid=65
/marcus.
Do you use the existing USB port? You could get one of the Arduino Serial USB Boards and mount it in a convenient place or use a front panel mount similar to this
For a cool retro look use an LED but face it with a small glass bead. 
If you're a Star Trek fan you can use marbles glued over slightly smaller holes and back light them with an LED. ;D
Great tip! Thanks!
I dont know if you could get those in europe (EU), I'm based in Sweden and ordering from the USA is usually quite expensive, with import taxes.
But, I found out that Neutrik has a nice solution that can work for me, a reversible USB genderbender fitted in a XLR-housing, for panel mounting. And this one I can buy here, so I'll check those out.
Here is more info: http://www.neutrik.com/content/products/detail.aspx?id=210_1953788625&catId=CatMSDE_misc
The idea for the LED sounds nice. I have to try some of that stuff out, even though I'm not a Trekker, I'm more a Star Wars-guy.
/m.