This is an great thread! I really hope to see more people take this seriously and give it a shot!
Well, a banner / ad should at least show what it's about.
The Pandora Logo will only work if the one who sees the ad already knows about it.
I agree with Ed, that this is the eventual goal, however, there is no point in throwing up text to fill in white space if the overall design has no direction.
My suggestion is to first start with message that you want to communicate in your design. Ultimately, this doesnt have to be explicitly reflected in your creation, but it creates a good starting point. "Cool looking design!" doesnt always work. Rather, try to highlight certain keywords that the Pandora embodies. Words such as: freedom, exploration, journey, empowering, open, retro ... etc.
Get an idea in your head with how think that might work, THEN research!
Check out this website for an amazing collection logos and design work, see what they did.
http://dribbble.com/
For more inspiration, this is one of my favorite magazines.
http://www.idea-mag.com/en/publication/355.php
It often features masters of design and typography. Great for inspiration.
From there, start designing. The secret is to iterate and iterate. There are millions of ways to balance even the most simple of elements. What is your goal for eye movement. Is the design balanced? USE WHITE SPACE, dont fill it up.
You can work with my my colors, or you can choose your own. Dont just stick with RGB, check out
https://kuler.adobe.com/ to come up with a good combination that expresses exactly what you want it to.
Once you've come up with a design language, then you can experiment with text placement. Consider what your audience is. Is this for print? A web ad? Where will it be featured? A forum signature? Should you list the specs, or try to summarize the Pandora with a fetching tag line?
Iterate, iterate, iterate! And share!
I'm quite passionate about this whole PR thing, I'm excited there might be other people in this community who are as well.