Gone are the days of the light grey mega monster under your desk. If you are the handy type of person, you can built your own PC and use one of these Tower enclosures to display, rather than hide, your masterpiece.

H2 Classic Silent Midtower Chasis
This case design comes with 8 front facing HDD's for better airflow, and great deal of sound dampening material to make sure your experience is a quiet one. We love the Touch Powered fans with 30W 3-Step control and that you can hot swap the top hard drive. These are mid-tower enclosures specially designed for gamers but we can see them being use at home as a main computer

Obsidian Series 650D
This one is more for the hardcore gamer and builder and made of stamped steel. We love the monolithic design and the black textured paint. The brushed front plate brings some elegance to the overall design. We always loved a display panel on the side and this one doesn't disappoint. With 8 expansion slots and several MB support, you are covered on your next built.

LIAN LI V COOL PC-V1000 Silver Aluminum ATX Mid Tower
This is one of our favorites, even that it shows as discontinued, but with a little more digging, you can find them elsewhere. This are pretty stylish case; and the use of real aluminum is a plus. Design cues from the elements of the MacPro, like the flush drive doors and perforated surfaces, put this one on the top of the "want list".

Thermaltake’s Level 10 case
This is the Lamborghini of computer cases. More like a work of art, these cases showcase engineering gone beyond performance; utilizing air flow management system and open architecture for internal components. You can bet there is some German engineering here, since BMW was part of the project. Cues from Formula 1 and Aerospace concepts are visible on this state of the art case. 9 drive bays, front and rear air intake via 140mm LED fans, asymmetrical balance and integrated handles, are just a few features of the Thermaltake’s Level 10 case.

Shaw's Original Fir...
I can understand builders putting the extra money into a stylish case, even though it has nothing to do with performance; but why would anybody want to put a lot of money into a case that has "design cues ... from the MacPro?"
And any case at the top of your "want" list would be the one that looks like a Mac.
I have to disagree with @Rckmnr. The case at the top of my want list looks nothing like a Mac. Currently hacked my old Alienware case with bamboo plus lexan. First comment was, "it looks like something out an eco-Tron". I get it, Apple has good products (which I own), but without my PC I wouldn't get much done either. Can't we all just get along?
I wouldn't go with the Lian Li because it is so old. New cases are much better at cooling, are easier to change out hardware, and very often just work and look better.
The level 10 is a real clunker, not to mention it's deceptively big. It's a monster. It's way overpriced, and the hinged bays sag when the doors are open. You would think that for $700 it would have none of these problems.
Antec cases have been very well made in our experience. Some of them are even good looking. Many, many pc cases are hideous.
I second the Antec case recommendation. I have an Antec Solo case which I got in 2007. Reasonably quiet, lots of nice features, not terribly expensive. Not beautiful, but certainly more tasteful than most (including the fugly, noisy cases Dell and HP shove most of their computers in).
But my next machine will likely be an iMac. With the arrival of Thunderbolt, I just don't see the need for a huge box with lots of internal expansion ports. My backups already live on external drives and in the cloud (thanks to CrashPlan), so I don't need a case that can house a bunch of drives.
On the off chance I actually need to expand the graphics or some other hardware, that should all be possible thru Thunderbolt.
I think the desktop PC as we know it will pretty much cease to exist over the next 10 years. I would say they'll survive as workstations and gamer rigs, but the reality is both of those functions would probably be better served by more power remote servers living in a public or private cloud.
I have the Raven01. I LOVE my case. The motherboard is mounted so the IO ports come out of the top. This creates less air flow issues with the video cards etc. The thing runs incredibly cool and I think it looks awesome. It reminds me of a Cylon with blue eyes. It is HUGE though. :-)
http://www.silverstonetek.com/raven/products/index.php?model=RV01
Fractal Designs makes some really tasteful and minimal cases, check those out. They also have some nice cable management and are really well reviewed.
I'm a mac user but thinking about building a hackintosh tower, and I'm amazed that its so hard to find a decent looking case with features to match. Apple has had one tower design for years and its amazing.
@SillyMo - I also really love the Silverstone cases that mount with the I/O plate at the top. They are really nice.